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TRANSCRIPT
Published in: The Mental Lexicon 3, pp. 149-175, 2008.
The Time-Course of Morphological Constraints:
A Study of Plurals inside Derived Words
Ian Cunnings Harald Clahsen
(University of Essex)
© John Benjamins Publishing Company, 2008. Corresponding Author: Harald Clahsen Department of Linguistics University of Essex Colchester, C04 3SQ, UK email: [email protected] Tel: +44/1206/87-2228 Fax: +44/1206/87-2198
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Abstract
The avoidance of regular but not irregular plurals inside compounds (e.g. *rats eater vs.
mice eater) has been one of the most widely studied morphological phenomena in the
psycholinguistics literature. To examine whether the constraints that are responsible for this
contrast have any general significance beyond compounding, we investigated derived word
forms containing regular and irregular plurals in two experiments. Experiment 1 was an
offline acceptability judgment task, and experiment 2 measured eye movements during
reading derived words containing regular and irregular plurals and uninflected base nouns.
The results from both experiments show that the constraint against regular plurals inside
compounds generalizes to derived words. We argue that this constraint cannot be reduced to
phonological properties, but is instead morphological in nature. The eye-movement data
provide detailed information on the time-course of processing derived word forms indicating
that early stages of processing are affected by a general constraint that disallows inflected
words from feeding derivational processes, and that the more specific constraint against
regular plurals comes in at a subsequent later stage of processing. We argue that these results
are consistent with stage-based models of language processing.
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1. Introduction
Morphological systems are constrained in how inflectional, derivational, and compounding
processes may interact with each other. There is, for example, a general tendency for
inflectional suffixes to attach outside derivational ones, which is captured by Greenberg’s
(1966: 93) Universal 28: ‘If both the derivation and inflection follow the root, or they both
precede the root, the derivation is always between the root and the inflection’. Thus in
English, forms such as ducklings with the plural suffix appearing after the derivational suffix
are grammatically well-formed but not forms with the reverse order (*ducksling).
Linguists have analyzed the interaction between different morphological processes in terms
of affix-specific selectional restrictions (see e.g. Fabb 1988, Plag 1996, 1999, 2002) and
other kinds of more general constraints (of a semantic, phonological, and morphological
nature) on how inflectional, derivational, and compounding processes may feed each other
(see e.g. Kiparsky 1982, Wiese 1996, Anderson 1992, Stump 2001). In English, the
observation that the denominal suffix –y never attaches to an already suffixed word (Fabb
1988), as in *duckling-y, is an example of an affix-specific selectional restriction. A well-
known example of a more general morphological constraint states that regularly inflected
forms such as –s plurals are blocked from productive derivational processes and from
compounding (Kiparsky 1982), hence the ungrammaticality of forms such as *ducks-less or
*ducks eater.
From a psycholinguistic perspective, the question arises as to how these kinds of constraints
affect the processing of morphologically complex word forms in real time. Specifically, we
ask at which point in time different kinds of constraints become operative. Previous
psycholinguistic research investigating the interaction of different morphological processes
has focused on the feeding relationships between inflection and compounding, the so-called
plurals-in-compounds effect (Senghas, Kim & Pinker. 2005). Several off-line rating and
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production studies (Gordon 1985, Haskell, MacDonald & Seidenberg 2003, Berent & Pinker
2007, among others) have found a response pattern indicating a general dispreference for
compounds containing plural non-heads (irrespective of regularity) in comparison to those
containing singulars, and an additional dispreference for compounds containing regular
plurals. In judgment tasks, for example, both regular and irregular plurals have been found to
be less acceptable inside compounds than singulars (fleas/lice remover vs. flea/louse
remover) and regular plurals have been found to be less acceptable than irregular plurals
(fleas remover vs. lice remover). In an eye-movement study, Cunnings and Clahsen (2007)
found that early eye-movement measures showed enhanced reading times for compounds
containing regular plural non-heads only, whilst later measures revealed an additional effect
for irregular plural versus singular non-head nouns. Whilst the general preference for
singular non-heads has been ascribed to a semantic constraint against compound-internal
modifiers with plural meaning (Haskell et al. 2003, Berent & Pinker 2007), the interpretation
of the contrast between regular and irregular plural modifiers is controversial. Some authors
have argued that this contrast is due to the phonological properties of regular plural nouns,
such that there is a specific dislike of compound-internal modifiers that end in s or z (Haskell
et al. 2003), or a result of the higher phonological overlap between a regular plural and its
corresponding singular form than between an irregular plural and its corresponding singular
form (Buck-Gengler, Menn & Healy 2004). Others have argued that this contrast is due to a
morphological constraint against regular plural modifiers inside compounds (see e.g.
Aronoff 1976, Kiparsky 1982, Di Sciullo & Williams 1987, Borer 1988, Pinker 1999).
In contrast to compounding and inflection, there is very little experimental research on the
interaction of inflectional and derivational processes. Marshall and van der Lely (2007)
performed an elicited production experiment in which children with Specific Language
Impairment (SLI) were found to sometimes include the inflectional suffix –s inside a
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denominal adjective with –y when presented with a plural stimulus (i.e. with a picture
showing multiple objects of a given kind), producing forms such as *stars-y, whereas
unimpaired children almost never did so, even when prompted with a plural stimulus. This
finding was taken to indicate that children with SLI treat plural forms such as stars as
unanalyzed wholes which as such may feed derivation. Apart from this one study, which
crucially did not compare regular to irregular plurals inside derived words, we are not aware
of any other experimental investigation on how inflectional and derivational processes
interact.
The present study aims to fill this empirical gap. We report results from two experiments, an
acceptability judgment task examining whether inflected forms inside derivations exhibit the
same contrasts between regulars and irregulars and between singulars and plurals that have
been found for compound-internal inflected forms, and an eye-movement experiment
examining the processes involved in the on-line comprehension of inflections inside
derivations.
2. Constraints on inflections inside derivations in English
Derivational affixes can be combined with each other in English, subject to a number of
constraints. Whilst, for example, combinations of the suffixes –less and –ness, and –ic and
-ity are grammatically well-formed (e.g. atom-less-ness, atom-ic-ity), the combination
-less+–ity is not possible (compare *atom-less-ity with atom-less-ness). These combinatorial
properties have been described in terms of affix-specific selectional restrictions (Fabb 1988,
Plag 1996, 1999, 2002) akin to the selectional restrictions of verbs, adjectives and other
kinds of lexical items. For example, the affix –ness may select derivational stems with –less
(yielding atom-less-ness), the affix –ity stems with –ic (yielding atom-ic-ity), but not the
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other way round. In this way, selectional restrictions may determine the possible and
impossible combinations of different affixes.
Apart from these kinds of affix-specific restrictions, derivational processes are also subject to
a general restriction that permits uninflected and disprefers inflected forms inside derived
forms yielding contrasts such as flealess vs. *fleasless, rocky vs. *rocksy, or louseless vs.
?liceless. Given realization-based models of morphology, such as Anderson (1992),
Matthews (1991) and Stump (2001), these contrasts can be derived from a Category
Constraint on the kinds of morphological types or categories that may enter derivational
processes. Realization-based models distinguish between rules that define derivational stem
entries from those that define inflected word forms. Derivational rules map one stem entry
onto another entry. A derived entry (e.g. duckling) may provide the input to subsequent
derivational rules (e.g. duckling-less), or may provide the base for the application of
inflectional rules (duckling-s). In contrast, inflectional rules are simple feature-form
mappings that specify the form that ‘realizes’ or ‘spells out’ a particular set of features. Sets
of inflectional rules are partitioned into ordered blocks or paradigms with the forms defined
by each rule block being passed to the next block without at any point being represented in
lexical entries. This implies that the outputs of inflectional rules (= word forms) do not
provide the input required for derivational processes (= stem entries), hence the
ungrammaticality of forms such as *ducksling. Thus, from the perspective of realization-
based models of morphology, the Category Constraint is a consequence of the different
nature of inflectional and derivational processes.
In addition to the preference of uninflected over inflected forms inside derivations, native
speakers of English when informally asked to make a choice between a regular and an
irregular plural inside a derived form, e.g. *fleasless vs. ?liceless, tend to find the latter more
acceptable than the former. This could mean that derivational processes are subject to the
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same constraint that blocks regularly inflected forms from appearing inside compounds;
compare, for example, *fleas eater vs. ?lice eater. As mentioned above, the nature of this
constraint is controversial. Some researchers (Buck-Gengler et al. 2004, Haskell et al. 2003)
have argued that the contrast between regular and irregular plurals inside compounds is due
to the surface form properties of regular plurals, e.g. the dispreference of compound-internal
modifiers that end in s or z (Haskell et al. 2003). Note, however, that English has a number
of uninflected bare nouns that share the phonological characteristics of regular plurals, e.g.
fox, box, hose, tax, etc., and these have been found to be fully acceptable inside compounds
(Berent & Pinker 2007). The same contrast seems to hold for derived words. Compare, for
example, *dogsless vs. wolfless and foxless, of which the latter two appear to be equally
acceptable even though foxless has the same stem-final phonology as the ungrammatical
regular plural (dogs) inside the derived form. Given these data, a purely phonological
account of the contrast between regular and irregular plurals inside compounds and derived
forms appears to be difficult to maintain (see Cunnings & Clahsen 2007 for further
discussion).
More commonly, the interaction of regular and irregular inflection with compounding and
derivation has been analyzed in morphological terms. Kiparsky (1982) proposed a theory of
morphological representation that includes a Level Ordering component which orders
irregular inflection before, and regular inflection after, compounding and (productive)
derivation. This component prevents regular inflectional affixes from appearing inside
compounds or inside productive derived forms. Several subsequent accounts have attempted
to reformulate the descriptive insights of Kiparsky’s model in terms of other distinctions (see
e.g. Di Sciullo and Williams 1987, Borer 1988, Wiese 1996, Pinker 1999). For derivational
morphology, Hay (2002, 2003) argued that the possible and impossible combinations of
derivational suffixes in English are determined by a parsability constraint according to which
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‘an affix that can be easily parsed out should not occur inside an affix that cannot’ (Hay
2002: 528). Consequently, highly decomposable suffixes tend to occur towards the periphery
of words rather than inside less decomposable ones. Whilst the notion of parsability was
originally proposed to explain the combinatorial properties of derivational suffixes, it may in
principle be extended to account for the contrast between regular and irregular plurals inside
derived forms in English. Regular plural forms are highly decomposable and given the
parsability constraint less likely to occur in a derived word than irregular plurals which are
typically suppletive forms and not decomposable. Hence ratsless is intuitively less
acceptable than miceless.
Taken together, we hypothesize that the interaction of inflectional and derivational processes
is subject to two different constraints, a general Category Constraint that disprefers all kinds
of inflected forms inside derived forms and an additional (morphological) Structure
Constraint that prevents regularly inflected forms (which are morphologically structured and
decomposable) from feeding any further word-formation processes. Given these constraints,
we would expect to find differences in acceptability ratings of derived forms such as (i)
flealess/louseless, (ii) liceless and (iii) fleasless. Forms with uninflected bare stems (i) should
receive the highest acceptability ratings, because they do not violate any of the constraints.
Derived forms such as (ii) violate the Category Constraint but not the Structure Constraint
and may therefore be marginally acceptable. Finally, forms such as fleasless violate both
constraints and should therefore be the least acceptable. Whilst introspectively these
distinctions appear to be correct, the purpose of Experiment 1 was to examine these
intuitions more systematically in an acceptability judgment task of derived words containing
base nouns that were the singular and plural forms of nouns that take regular and irregular
inflections.
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3. Morphological constraints during language processing
Psycholinguists attempt to specify at which point in time particular sources of information
become available during on-line language comprehension. Broadly speaking, we can
distinguish between serial and parallel-interactive models of language processing. Serial
models claim that language comprehension involves a sequence of stages and that the
computation of structural (morpho-syntactic) information precedes the computation of
semantic and pragmatic information (e.g. Frazier & Fodor 1978, Rayner, Carlson & Frazier
1983, McElree & Griffith 1998, Frazier & Clifton 1996, Binder, Duffy & Rayner 2001). The
alternative parallel-interactive view holds that language comprehension at any given point in
time is affected by all relevant sources of information (e.g. Altmann, Garnham & Dennis
1992, Thornton, Gil & MacDonald 1998, Spivey, Fitneva, Tabor & Ajmani 2002).
Given that the interaction of inflectional and derivational processes in morphologically
complex words is subject to constraints and that these constraints rely on different kinds of
information, time-course issues also arise for the processing of derived word forms. The
Category Constraint, for example, excludes certain kinds of objects (inflected words) from
feeding derivational processes, whilst the Structure Constraint specifies their internal
structure, ruling out regularly inflected combinatorial forms from appearing inside derived
word forms. Given these constraints, the question arises as to at which point in time they
affect the processing of a derived word form. Does the Category Constraint become available
earlier in time than the Structure Constraint, or vice versa, or are both constraints employed
in parallel? To our knowledge, the interaction of inflectional and derivational processes
during on-line processing has previously not been investigated. However, by extrapolating
from previous sentence-processing research, we can think of two possibilities of how these
constraints may affect the on-line processing of derived words. One possibility is that all
relevant constraints apply in parallel and that corresponding effects are seen at both early and
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late stages of processing. This would fit in with parallel-interactive models of sentence
processing in which all relevant information sources are used the moment they are received
as input (Spivey, Fitneva, Tabor & Ajmani 2002; 208). An alternative possibility is that the
two constraints on derived word forms become available at different points in time during
processing, which would be consistent with stage-based models of sentence processing.
Friederici (2002), for example, proposed a model according to which word-category
information is processed earlier than other aspects of morpho-syntactic structure. If this
extends to morphologically complex words, we may find effects of the Category Constraint
at earlier stages of processing than effects of the Structure Constraint. These different
possibilities were examined in Experiment 2 by recording eye-movements during reading, a
technique that provides a rich source of data on moment-to-moment language processing
(Rayner 1998).
4. Experiment 1: Acceptability judgments
The purpose of this experiment was to examine whether forms such as (i) flealess/louseless,
(ii) liceless, and (iii) fleasless show the same distinctions in acceptability ratings that have
previously been found for inflected and non-inflected forms inside compounds. Moreover, as
pointed out above, the nature of the plurals-in-compounds effect is controversial, with some
authors claiming that it is due to a phonological constraint (e.g. against modifiers ending in
s/z) and others arguing that it is morphological in nature (e.g. banning compound-internal
inflected words with a combinatorial structure). We therefore adopted the acceptability rating
task from previous studies of compounding (e.g. Haskell et al. 2003, Senghas et al. 2005,
Berent & Pinker 2007) to examine derived words such as those in (i) to (iii), and to test
whether any dissociation between regular and irregular plurals inside derived words is best
characterized in morphological or phonological terms.
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Method
Participants
40 native English speakers (11 males, mean age 24.8) from south-east England voluntarily
took park in this experiment.
Materials
All experimental items were derived words constructed by attaching a single derivational
suffix, adjective-forming -less and adverb-forming -wise, to a base noun. There were two
sets of experimental items treated separately for analysis purposes. Experimental item set 1
was constructed to examine the acceptability of derived words containing the singular and
plural forms of base nouns that take regular and irregular inflections. Nine nouns that take
irregular plural forms and nine nouns that take the regular plural –s were chosen, which were
as closely related in meaning as possible (e.g. irregular goose/geese was matched with
regular duck/ducks). The singular forms of these nouns were matched for frequency, length
in letters and number of syllables, using the CELEX Lexical Database (Baayen, Piepenbrock
& van Rijn 1993). For the frequency matching, the word-form frequency of the singular
forms of the nouns that take irregular plurals was matched with the lemma frequency of the
nouns that take regular plurals. This was done to do justice to the linguistic differences
between regular and irregular plurals in English. Irregular plurals are largely suppletive
forms whereas regular -s plurals are fully transparent forms with a segmentable ending and
no stem changes. One would therefore expect that the recognition of irregular plural forms is
mainly affected by word-form frequency, whereas the recognition of regular plurals should
be affected by lemma/stem frequency; see Sonnenstuhl & Huth (2002) for evidence from
German noun plurals supporting this contrast. Overall, the items were tightly controlled for
these three matched variables. The mean frequency per million of the irregular and regular
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nouns was 207.67 and 204.67 respectively, mean length in letters for the irregular and
regular nouns was 4.33 and 4.22 respectively, and mean number of syllables for the irregular
and regular nouns was 1.11 and 1.33 respectively. A series of between-items t tests indicated
that there were no significant differences between the singular forms of the irregular and
regular nouns, for any of the three matched variables (all t < 1.33, all p > .208). A full list of
items can be found in Appendix A. Both the singular and plural forms of each noun were
tested with the two derivational suffixes -less and -wise, creating a total of 72 items in four
conditions (with 18 items per condition): (i) singular forms of nouns that take irregular
plurals (singular/IRREGULAR, e.g. gouseless), (ii) irregular plural forms
(plural/IRREGULAR, e.g. geeseless), (iii) singular forms of nouns that take regular plurals
(singular/REGULAR, e.g. duckless), (iv) regular plural forms (plural/REGULAR, e.g.
ducksless).
Experimental item set 2 was constructed to examine the effects of base noun phonology on
the acceptability of derived words. All items in experimental item set 2 were singular nouns.
Eight nouns that phonologically resemble regular plurals and eight nouns that are
phonologically distinct from regular plurals were chosen, which were as closely related in
meaning as possible (e.g. box was matched with crate). These nouns were additionally
matched for lemma frequency per million, length in letters and number of syllables. The
mean frequency, mean length in letters and mean number of syllables of the nouns that
phonologically resembled regular plurals was 32.13, 4.25 and 1.25 respectively, whilst the
mean frequency, mean length in letters and mean number of syllables of the nouns that were
phonologically distinct from regular plurals was 33.88, 4.13 and 1.00 respectively. A series
of between-items t tests revealed no significant differences between the two types of noun,
for any of the three matched variables (all t < 1.53, all p > .148). A full list of items can be
found in Appendix B. As with experimental item set 1, the two derivational suffixes –less
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and –wise were attached to the base nouns of experimental item set 2. As only the derived
forms containing the singular forms of each noun were tested, experimental item set 2
consisted of a total of 32 derived words in two conditions (with 16 items per condition): (i)
singular forms of nouns that end in codas phonologically identical to regular plural forms
(phon./SIM, e.g. boxless), (ii) singular forms of nouns that end in codas phonologically
dissimilar to regular plural forms (phon./DIS, e.g. crateless).
In addition to the two sets of experimental items, 40 filler items were constructed, all of
which were morphologically complex words containing a variety of affixes and affix
combinations. 10 of the filler items were acceptable complex words using attested affix
combinations in the language (e.g. fatherly, undriveable), whilst a further 10 fillers were
unacceptable complex words, using unattested affix combinations (e.g. oddnessity,
strongity). An additional 10 fillers were constructed which were unacceptable complex
words containing various suffixes, all of which were attached to nouns in their plural form
(e.g. parentshood, apesdom). A final 10 unacceptable filler items were constructed by
attaching various deverbal suffixes to verbs which appeared in their past tense form (e.g.
sailedable, drover).
A series of short two-sentence context paragraphs were constructed within which all
experimental and filler derived words were inserted (see (1)). The derived words always
appeared in the second sentence of the context paragraphs, in bold capital letters to ensure
their salience within the texts. For experimental item set 1, context paragraphs were
constructed such that a derived word from each of the four conditions could be placed
felicitously into an identical context paragraph. The same procedure was adopted for the two
conditions of experimental item set 2.
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(1) a. Experimental item set 1, -less form:
Following recent food scares regarding British meat, the Government has advised
farmers to slaughter much of their livestock. One local farmer has been left
completely OX(EN)/PIG(S)-LESS since the cull was recommended.
b. Experimental item set 1, -wise form:
Many dog owners have problems keeping their pets free from mites and other itchy
pests. LOUSE(LICE)/FLEA(S)-WISE, our dog has luckily never had such
problems.
c. Experimental item set 2, -less form:
My sister recently moved, and was annoyed with all the storage containers cluttering
up her new home. Although the house has been completely BOX/CRATE-LESS for
a week now, she’s still having trouble settling in.
d. Experimental item set 2, -wise form:
Wild animals always seem to terrorise local farmers by eating most of their livestock.
WOLF/FOX-WISE, there has been a particularly worrying amount of trouble this
year.
Procedure
Four lists were created such that each participant saw each context paragraph only once with
each list containing 34 experimental items and 40 fillers. The experimental and filler items
were presented in the same pseudo-randomized order for each list, with no experimental
items from the same condition appearing adjacent to each other. Participants were instructed
to simply read each context paragraph and then rate the acceptability of the derived word
only, on a scale from 1 (highly unacceptable) to 7 (highly acceptable). Each list was
completed by the same number of participants.
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Results
The mean acceptability ratings (and standard deviations) for the derived words of the two
experimental item sets are shown in Table 1.
//INSERT TABLE 1 ABOUT HERE//
The results for experimental item set 1 indicate that derived words containing singular base
nouns received high acceptability ratings. By contrast, derived words containing regular
plurals were rated highly unacceptable and derived words containing irregular plurals
marginally acceptable. A two-way ANOVA with Regularity (irregular/regular) and Plurality
(singular/plural) as independent variables on the mean acceptability scores for experimental
item set 1 revealed significant main effects of Regularity (F1(1, 39) = 28.43, p < .001; F2(1,
68) = 13.60, p < .001) and Plurality (F1(1, 39) = 101.06, p < .001; F2(1, 68) = 76.66, p <
.001), and most importantly, a significant Regularity-by-Plurality interaction (F1(1, 39) =
21.03, p < .001; F2(1, 68) = 7.78, p = .007). Subsequent pairwise comparisons revealed that
there were no significant differences between the acceptability of derived words containing
the two different types of singular nouns (sg./IRR vs. sg./REG: t1(39) < 1, p = .530; t2(34) <
1, p = .587). Derived words containing irregular plurals were, however, rated significantly
less acceptable than derived words containing either type of singular noun (pl./IRR vs.
sg./REG: t1(39) = 6.03, p < .001; t2(34) = 3.65, p = .001; pl./IRR vs. sg./IRR: t1(39) = 5.99, p
< .001; t2(34) = 3.71, p = .001). Derived words containing regular plurals were also rated
significantly less acceptable than derived words containing either type of singular base
(pl./REG vs. sg./REG: t1(38) = 9.37, p < .001; t2(34) = 9.71, p < .001; pl./REG vs. sg./IRR:
t1(39) = 9.48, p < .001; t2(34) = 8.65, p < .001). Additionally, derived words containing
regular plurals were rated significantly less acceptable than derived words containing
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irregular plurals (pl./REG vs. pl./IRR: t1(39) = 5.61, p < .001; t2(34) = 5.65, p < .001). These
results reveal a gradual pattern of responses with both regular and irregular plural base nouns
being less acceptable inside derived words than uninflected bare stems. Derived words
containing regular plurals are also less acceptable than derived words containing irregular
plurals.
As shown in Table 1, experimental item set 2 yielded almost the same acceptability ratings
of 5.08 for the phonologically similar condition and 5.07 for the phonologically dissimilar
condition (phon./SIM vs. phon./DIS: (t1(39) < 1, p = .974; t2(30) < 1, p = .994), indicating
that a singular noun that ends in the same segment as a regular plural did not have any
adverse effect on participants’ acceptability judgments.
Discussion
These results are parallel to what has previously been found for compounds. Recall that the
same contrasts we found for derived forms (with both regular and irregular plurals being less
acceptable inside derived words than singulars, and regular plurals being also less acceptable
than irregular plurals) have previously been obtained for inflected and non-inflected forms
inside compounds in a number of studies (Haskell et al. 2003, Senghas et al. 2005, Cunnings
& Clahsen 2007). Likewise, our finding that the phonological properties of singular base
nouns (in particular /s/ final codas) had no reliable effect on the acceptability of the derived
words is also parallel to Berent and Pinker’s (2007) observation that compounds such as fox
chaser are rated as being fully acceptable.
These findings could mean that compounding and productive derivational processes such as
–less and –wise suffixation are subject to the same constraints. For plurals inside compounds,
three constraints have been proposed. One proposal was a phonological constraint according
to which s/z-final words are dispreferred inside compounds (Haskell et al. 2003). Berent and
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Pinker (2007) provided evidence from compounds against such a constraint, and our results
clearly show that the low acceptability ratings of regular in comparison to irregular plurals
inside derived forms with -less and -wise cannot be explained in phonological terms. More
commonly, the dislike of regular plurals inside compounds has been attributed to a constraint
of morphological structure (see e.g. Kiparsky 1982, Di Sciullo and Williams 1987, Wiese
1996, among others). Our results indicate that this constraint also affects derivation, thus
confirming Kiparsky’s (1982) original insight that regular inflection is ordered after all other
word-formation processes and can therefore not feed either compounding or derivation.
A further constraint has been proposed for compounds to capture the fact that compounds
containing singular nouns as non-heads are preferred over plural forms of any kind,
irrespective of regularity. Haskell et al. (2003) argued that this contrast is due to a semantic
constraint against compound-internal modifiers with plural meaning. Specifically, the
semantics of compounds requires that the relationship between the referents of the two
elements of a compound is interpreted such that the non-head element of a compound
typically refers to a kind, not an individual. For example, a garden hose can be used for
gardens in general, not for a particular kind or number of gardens. Given that in English, a
singular noun form is identical to a bare nominal stem, the form which is not explicitly
marked for NUMBER is more acceptable inside a compound than a plural form. Moreover,
plural NUMBER semantics has been shown to affect the extent to which a plural noun is
admissible inside a compound. In compounds such as publications catalogue, for example,
the plural non-head refers to multiple distinct entities (i.e. publications) within a
heterogeneous collection of individuals, and in such cases even a regular plural form can be
fully acceptable (see Alegre & Gordon 1996, 1999; Pinker 1999). These considerations do
not seem to apply to derived words. Compounds consist of a modifier and a head and may
therefore be affected by a semantic constraint that specifies the relationship between
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different referents of the modifier and the head of a compound. Derived words, however,
consist of a base and one or more affixes. Derivational affixes do not have referents, and the
base of a derived word does not constitute a ‘modifier’ of any kind. Consequently, the
semantic constraint as proposed for compounds does not apply to derived words. Instead,
derivational affixes are subject to selectional restrictions, some of which are affix-specific
and others more general. As mentioned above, one such general constraint restricts the kinds
of morphological types or categories that may enter derivational processes to stems.
According to this Category Constraint, uninflected stems are preferred and all kinds of
inflected words dispreferred inside derived forms yielding contrasts such as flealess vs.
*fleasless or louseless vs. ?liceless.
Summarizing, we propose that derived words are subject to a Category Constraint and to the
same (morphological) Structure Constraint that applies to compounds. Derived words
containing uninflected stems (flealess) do not violate any of these constraints and are fully
acceptable, whilst those containing regular plurals violate both constraints and are
ungrammatical (*fleasless), and derived words containing irregular plurals violate the
Category but not the Structure Constraint and as such are marginally acceptable (?liceless).
In this way, the two constraints account for the performance pattern seen in the present
experiment.
5. Experiment 2: Eye-movements during reading derived words
The aim of this experiment was to examine the time-course of the constraints on derived
word forms investigated in the acceptability judgment task reported above. Participants read
a series of paragraphs containing derived words similar to those tested in Experiment 1,
whilst their eye-movements were monitored. From the perspective of stage-based models of
language processing, one would expect that violations of the Category Constraint (against
19
inflected words inside derivations) should lead to increased reading times from the earliest
possible measures, whereas violations of the Structure Constraint (against regular inflection)
should be recognized later (see section 3 above). Alternatively, we may find that the two
constraints affect reading-time measures in parallel, a result which would be more
compatible with parallel-interactive models of language processing.
Method
Participants
Twenty-four native English speakers (12 males, mean age 21.8) with normal or corrected to
normal vision from the University of Essex student community were paid to participant in
Experiment 2, none of whom took part in Experiment 1.
Materials
Experimental items consisted of 54 novel derived words in three conditions, containing (i)
irregular plurals (e.g. oxenless), (ii) regular plurals (animalsless), (iii) singular nouns
(horseless). Unlike in experiment 1, we used different base nouns for these three conditions
as it is impossible to match the singular and plural forms of the same base noun (e.g. rat and
rats) for length, a variable that has been shown to have an immediate effect on processing
times during reading (Rayner 1998). Instead, nine irregular plural nouns were matched with
nine regular plural nouns and nine singular nouns. Although the base nouns differed between
conditions, they were matched as closely as possible for a number of lexical variables that
may potentially influence reading times. These included frequency, length in letters and
number of syllables using the CELEX lexical database. As in experiment 1, word-form
frequencies were used for the irregular plurals items, whilst lemma frequencies were used for
the regular plural and singular items, in accordance with the linguistic differences between
20
regular and irregular plural forms in English. The mean frequencies per million were 238.22,
239.78 and 235.78 for the irregular plural, regular plural and singular conditions
respectively. The mean length in letters was 4.67, 4.67 and 4.33, and the mean number of
syllables was 1.33, 1.22 and 1.33 for the irregular plural, regular plural and singular
conditions respectively. A series of between-items one-way ANOVAs revealed that there
were no significant differences between the three conditions for any of the three matched
variables (all Fs < 1, all ps > .791). Appendix B contains frequency and length information
for all nouns used. In addition, the items were matched with respect to concreteness and
familiarity, two variables which correlate with reading times (Juhasz & Rayner 2003). Two
one-way ANOVAs revealed that the base nouns in each condition did not differ in either
concreteness or familiarity (both Fs <1, both ps > .790), in terms of the measures provided
by the MRC Psycholinguistic Database1 (Wilson 1988). Furthermore, there were also no
significant differences between conditions in terms of the base nouns’ mean lexical decision
times and naming latencies2 (both Fs < 1, both ps > .397), as provided by the English
Lexicon Project (Balota, Cortese, Hutchison, Neely, Nelson, Simpson & Treiman 2002). We
thus maintain that the base nouns between conditions were very closely matched for a
number of variables that could potentially influence reading times.
Each noun was affixed with two derivational suffixes, adjective-forming –less and adverb-
forming suffix -wise, creating a total of 54 experimental items, with 18 items per condition
(e.g. oxenless, animalsless, horseless and oxenwise, animalswise, horsewise). Of all the
critical derived words we tested, only one occurs in CELEX (faceless), with a low word-
form frequency of 2 per million. Furthermore, none of the -less or -wise forms containing
irregular or regular plural base nouns were attested in the much larger (100 million word)
British National Corpus (BNC), even though compounds containing irregular plural non-
heads, such as lice infestation, and even regular plurals, such as buildings inspector, are
21
found in the corpus. Of the -less and -wise forms with singular base nouns, only one token
with -wise occurred in the entire corpus (facewise) and six forms with -less (fishless, dogless,
handless, husbandless, faceless), all of which had very low token frequencies of close to zero
per million in the BNC. Thus, although we cannot rule out the possibility that participants
may have previously encountered some of the derived words, it is maintained that all are
sufficiently low in frequency to minimize potential whole-word frequency effects.
To ensure a felicitous reading of the derived words, short three-sentence context paragraphs
were created for all experimental and filler items. For each triplet of items (e.g. oxenless,
animalsless and horseless formed one triplet), three different context paragraphs were
constructed, within which each critical item could be placed felicitously. Each context
paragraph began with a sentence that introduced a character and continued with a second
sentence that always included the critical derived word. Each derived word appeared towards
the middle of the second sentence, and was always preceded by a pre-target word of between
6 and 12 letters long. The pre-target word was chosen to be of this length to aid the
probability of the target word receiving a progressive first fixation during its first pass. The
third sentence was a simple wrap-up sentence to soak-up any end of trial effects. Each
sentence of each context paragraph took up one line onscreen. An example of an
experimental triplet of context paragraphs is shown in (2):
(2) a. Example context 1:
Our dog was pest infested until we treated him with a special shampoo.
He's since been completely LICE/MITES/FLEALESS and has stopped itching all over.
If he has similar problems in the future we now know what to do.
b. Example context 2:
Our dog Max often has pest problems and is always scratching himself.
22
However, he's been totally LICE/MITES/FLEALESS since we bought a pest shampoo.
He hasn't scratched himself since we used the shampoo last Wednesday.
c. Example context 3:
Our cat is usually covered in pests as she loves playing in our bins.
However, she's been practically LICE/MITES/FLEALESS since we removed the bins.
Now that she can't get to the trash, we hope she won't itch as much.
In addition to the experimental items, 60 filler texts comprised of a variety of different
syntactic constructions were created. Each filler text took up to three lines onscreen, half of
which contained two sentences, and half of which contained three sentences.
To ensure that the critical items displayed the intended range of acceptability, the 54
experimental context paragraphs were pre-tested with 21 native English speakers (6 males,
mean age 28.1) from the University of Essex student community, none of whom took part in
any of the other experiments. In this pre-test, the 54 critical items were interspersed with 40
fillers that contained a variety of acceptable and unacceptable derived words. Three pseudo-
randomized lists were created such that no critical items from the same condition appeared
adjacent to each other, and each list was distributed to the same number of participants, who
rated the acceptability of the derived words only on a scale from 1 (unacceptable) to 7 (fully
acceptable). The mean acceptability ratings of the experimental items were as follows.
Derived words containing singular base nouns received a high overall mean acceptability
rating of 4.67, whilst those containing regular plural base nouns received a low mean
acceptability rating of 1.92. Derived words containing irregular plural base nouns received a
marginally acceptable mean rating of 3.47. A one-way ANOVA revealed a significant main
effect of base noun type (F1(2, 40) = 74.52, p < .001; F2(2, 51) = 148.10, p < .001), and
subsequent pairwise comparisons revealed significant differences between each of the three
23
conditions (4.67 vs. 3.47: t1(20) = 6.49, p < .001; t2(34) = 6.83 < .001; 4.67 vs. 1.92: t1(20) =
9.95, p < .001; t2(34) = 16.43, p < .001; 3.47 vs. 1.92: t1(20) = 7.52, p < .001; t2(34) = 11.49,
p < .001). These pre-test results confirm the findings of Experiment 1 for the materials to be
used in the eye-movement experiment.
Procedure
For the main experiment, three lists were constructed such that each participant saw each of
the 54 experimental items, and each context paragraph only once. The 54 experimental items
were pseudo-randomised with the 60 fillers such that no two experimental items from the
same condition appeared adjacent to each other. In addition, the ordering of the three
versions of the experiment were reversed, making a total of six experimental lists, which
were all completed by the same number of participants, with all derived word and context
paragraph combinations being seen by the same number of participants across lists.
Participants were instructed to read the sentences onscreen at their normal reading rate, and
press a button once completed. To ensure that participants properly attended to the sentences,
simple content questions requiring a yes/no push-button response were displayed after
approximately 20% of trials. Participants had few problems with the content questions,
giving correct responses with a mean accuracy of 89.2% (SD 7.82), indicating that they paid
attention to the content of the sentences.
Eye-movements were recorded using the head-mounted EYELINK II system from SR
Research Ltd., Canada. Stimuli were presented onscreen 80cm from the participants’ eyes,
and at this viewing distance one onscreen character subtended approximately one degree of
visual angle. The eye-tracker records participants’ eye-movements via two cameras mounted
on a headband placed over the participants’ head at a sampling rate of 500Hz, with spatial
accuracy better than 0.5 degrees. Participants’ head movements are automatically
24
compensated for via a third camera mounted in the centre of the headband, which tracks the
position of four LEDs mounted on the corners of the computer screen. Any head movement
is detected as movement of the LEDs, and is automatically compensated for online. Whilst
participant vision was binocular, the eye-movement record was recorded from the right eye
only. Before presentation of the main experiment, 5 practice trials were displayed onscreen
to familiarize participants with the experimental procedure. Participants were instructed to sit
still whilst reading, and were allowed breaks in-between trials if they so wished. The entire
experiment lasted approximately 40 minutes.
Data Analysis
Reading time measures were calculated for two regions of text. The pre-target region was
defined as the word directly preceding the derived word, plus half a letter space either side,
and the derived word region was defined as the derived word itself, plus half a letter space
either side. Whilst the derived word is the primary region of interest, reading times were also
calculated for the word directly preceding it to capture any potential effects of parafoveal
processing.
Five reading-time measures were calculated to provide a rich source of information
regarding the time-course of processing. First fixation duration refers to the duration of the
first fixation within a target region. Gaze duration is calculated by summing the duration of
all fixations, starting with the first fixation when the eyes first enter a region from the left, up
until the eyes first leave that region, either to the left or the right. Both of these measures are
believed to index the early stages of processing that accompany and immediately follow
lexical access, although gaze duration times may reflect later processing stages than first-
fixation durations, because large regions of text (including large words) often obtain more
than one fixation during their first pass. The third measure calculated was regression path
25
duration. This is calculated by summing the duration of all fixations, starting with the first
fixation when a region is entered from the left, up until but not including the first fixation
when the target region is first exited to the right. As this measure includes the duration of any
regressive fixations, regression path durations are usually longer than first fixation and gaze
durations, and can be seen to index slightly later stages of processing, perhaps those related
to the integration of the material in the current target region with the preceding text (Rayner,
Warren, Juhasz & Liversedge et al. 2004, Sturt 2003). The fourth measure calculated was
rereading time, the sum of all fixations within the target region after it has been exited to
either the left or the right for the first time. As such, this measure reflects later, second-pass
stages of processing which are somewhat delayed in relation to the measures defined above
that relate to a region’s first encounter. Finally, total viewing time is the summed duration of
all fixations within a target region, irrespective of whether they occurred during its first or
any subsequent passes. As such, this measure is a general index of processing load,
encapsulating both early and later stages of processing.
All measures were calculated contingent on a region gaining a progressive first fixation
during its first-pass. Trials in which a region was initially skipped were treated as missing
data. For rereading time, trials in which a region did not receive any subsequent refixations
following the first-pass were treated as contributing a rereading time of zero to the
calculation of averages. Fixations shorter than 50ms that were within one degree of another
fixation were merged together. All other fixations shorter than 50ms were discarded before
any further analysis, as little information is extracted during such short fixations (Rayner &
Pollatsek 1989). Before any further analysis was undertaken, trials in which track loss
occurred, or in which the target derived word region was directly fixated before reading of
the second sentence had begun, were removed. This amounted to the removal of 1.93% of
the critical trials, equally distributed across conditions.
26
Results
Analysis of the pre-target region is reported first. This region received a progressive first
fixation in 87.41%, 88.36% and 86.84% of trials in the irregular plural, regular plural and
singular conditions respectively. This amounted to an overall first-pass fixation probability
of 87.54%, with no significant differences between conditions (F1(2, 46) < 1, p = .826; F2(2,
51) < 1, p = .857). Mean durations of the five reading time measures calculated for the pre-
target region are shown in Table 2.
//INSERT TABLE 2 ABOUT HERE//
A series of one-way ANOVAs revealed no reliable differences between any of the
conditions, for any of the five reading time measures (all Fs < 1, all ps < .45). This indicates
that there were no reliable effects of the experimental manipulation on the reading times of
the pre-target region, either as a result of parafoveal processing of the derived word before its
initial inspection, or as a result of any subsequent additional processing incurred following
inspection of the derived word.
Consider next the results for the critical word. The derived word region received a
progressive first fixation in 96.95% of trials in the irregular plural condition, 95.06% of trials
in the regular plural condition, and 93.57% of trials in the singular condition. This amounted
to an overall first-pass fixation probability of 95.20%, and a one-way ANOVA revealed
reliable differences in skipping rates between conditions, at least in the subjects analysis
(F1(2, 26) = 3.23, p = .049; F2(2, 51) = 2.10, p = .134). Subsequent pairwise comparisons
indicated no significant differences in first-pass skipping rates between the regular plural and
irregular plural conditions (t1(23) = 1.64, p = .115; t2(34) = 1.38, p = .177), nor between the
regular plural and singular conditions (t1(23) = 1.03, p = .312; t2(34) < 1, p = .439).
27
However, first-pass skipping rates of the derived word were significantly higher in the
singular condition than in the irregular plural condition (t1(23) = 2.36, p = .027; t2(34) = 2.03,
p = .050). Whilst significant, this difference in skipping rates was numerically small (only
3.38%), and most likely not large enough to have any reliable effects on the reading time
measures reported below. Table 3 presents the main eye-movement data.
//INSERT TABLE 3 ABOUT HERE//
A one-way ANOVA revealed a significant main effect of base noun type on the first fixation
duration of the derived word region (F1(2, 46) = 7.79, p = .001; F2(2, 51) = 4.97, p = .011).
Subsequent pairwise comparisons revealed that derived words containing regular plurals had
a significantly longer first fixation duration than derived words containing singular base
nouns (t1(23) = 3.48, p = .002; t2(34) = 2.86, p = .007). Derived words containing irregular
plurals also had a significantly longer first fixation duration than derived words containing
singular bases (t1(23) = 4.23, p < .001; t2(34) = 2.84, p = .008). There were no significant
differences however between the first fixation duration of derived words containing regular
plural base nouns in comparison to those containing irregular plurals (t1(23) < 1, p = .695;
t2(34) < 1, p = .672). The same pattern of results was obtained for the gaze duration of the
derived words. A one-way ANOVA revealed a significant main effect of base noun type
(F1(2, 46) = 7.79, p < .001; F2(2, 51) = 6.09, p = .004), and subsequent pairwise comparisons
revealed significantly longer gaze durations for derived words containing regular plurals in
comparison to those containing singulars (t1(23) = 4.90, p < .001; t2(34) = 3.32, p = .002),
and also significantly longer gaze durations for derived words containing irregular plurals in
comparison to those containing singulars (t1(23) = 5.41, p < .001; t2(34) = 3.13, p = .004).
The gaze durations of derived words containing regular plural bases did not differ
28
significantly from those containing irregular plurals (t1(23) < 1, p = .837; t2(34) < 1, p =
.872).
A one-way ANOVA for the regression path duration revealed a significant main effect of
base noun type in the subjects analysis, that approached significance by items (F1(2, 46) =
5.32, p = .008; F2(2, 51) = 2.57, p = .087). Pairwise comparisons indicated that derived
words containing regular plural base nouns had significantly longer regression path durations
than derived words containing singular bases (t1(23) = 2.68, p = .013; t2(34) = 2.39, p =
.022). Derived words containing irregular plural base nouns also had longer regression path
durations than derived words containing singular bases, though this difference approached
significance in the subjects analysis only (t1(23) = 2.04, p = .053; t2(34) < 1, p = .368).
Finally, there was also a trend in the subjects analysis towards longer regression path
durations for derived words containing regular plural base nouns in comparison to those
containing irregular plurals (t1(23) = 1.79, p = .087; t2(34) = 1.32, p = .197).
For the rereading time data, a one-way ANOVA again revealed a significant main effect of
base noun type (F1(2, 46) = 9.37, p < .001; F2(2, 51) = 10.37, p < .001). Pairwise
comparisons revealed that derived words containing regular plurals had significantly longer
rereading times than both derived words containing singular bases (t1(23) = 3.81, p = .001;
t2(34) = 3.77, p = .001) and derived words containing irregular plurals (t1(23) = 2.96, p =
.007; t2(34) = 4.15, p < .001). There were, however, no significant differences between the
rereading times of derived words containing irregular plurals in comparison to those
containing singular base nouns (t1(23) < 1, p = .760; t2(34) < 1, p = .810).
Finally, a one-way ANOVA of the total viewing time data revealed a significant main effect
of base noun type (F1(2, 46) = 21.36, p < .001; F2(2, 51) = 10.31, p < .001), and subsequent
pairwise comparisons revealed significant differences between each of the three conditions.
Derived words containing irregular plurals had longer total viewing times than derived words
29
containing singular bases (t1(23) = 4.40, p < .001; t2(34) = 1.97, p = .057). Derived words
containing regular plurals also had longer total viewing times than both derived words
containing singular base nouns (t1(23) = 6.42, p < .001; t2(34) = 4.77, p < .001), and derived
words containing irregular plurals (t1(23) = 2.93, p = .008; t2(34) = 2.46, p = .019).
Summarizing the main finding of the present experiment, the experimental manipulation
gave rise to different reading time patterns for the critical derived word region. For the two
reading time measures which reflect processing time incurred during the initial inspection of
the target region (first fixation duration and gaze duration), longer reading times were
obtained for derived words containing plural base nouns, irrespective of regularity, in
comparison to derived words containing singular bases. In these two early first-pass
measures, no reliable differences were obtained between derived words containing regular
plurals in comparison to those containing irregular plurals. By contrast, the one processing
measure which specifically excludes the initial time spent in the derived word region
(rereading time) yielded longer reading times for derived words containing regular plurals in
comparison to those containing either irregular plurals or singulars, with no significant
differences between the latter two. Finally, the two reading time measures which index both
the initial time spent in the target region and any additional subsequent processing incurred
thereafter (regression path duration and total viewing time) yielded a gradual pattern of
responses, with short reading times for derived words containing singular base nouns,
followed by longer reading times for derived words containing irregular plurals, with derived
words containing regular plurals producing the longest reading times.
Discussion
These results indicate that the two constraints we examined affect different stages of
processing. The Category Constraint which permits uninflected and disprefers inflected
30
forms (irrespective of regularity) inside derived forms has an immediate effect on
processing, from the earliest stages of first-pass processing. The Structure Constraint against
regular plurals inside derived words, however, affects reading time measures indexing
subsequent later stages of processing. These differences correspond to different levels of
morphological analysis needed for detecting violations of these two constraints. Category
violations inside derived words, i.e., cases in which a derivational affix is combined with an
inflected word form rather than with a stem, can be immediately recognized once the
derivational suffix is stripped off. By contrast, detecting violations of the constraint against
regular inflections inside derived forms (and compounds) requires a more detailed analysis
of the internal structure of the base noun within a derived word.
Parallel-interactive models of language processing (see e.g. Thornton et al. 1998, Spivey et
al. 2002) claim that the language processor makes use of all relevant constraints in parallel
from the earliest stages of processing. From this perspective, one would have expected that
in all measures of processing, derived words containing singular nouns should yield the
shortest reading times (because these forms do not violate any constraint), followed by
derived words containing irregular plurals (due to the violation of one constraint), with
derived words containing regular plurals yielding the longest reading times (because these
forms violate both constraints). This pattern was indeed found for the offline acceptability
judgments, the total viewing times, and the regression path durations, but importantly, not
for those eye-movement measures that are sensitive to early stages of processing. Thus, the
prediction that all relevant constraints affect processing equally early was clearly
disconfirmed.
Our results appear to be more consistent with stage-based of models of language processing.
For concreteness, consider Friederici’s (2002) three-stage model of sentence processing
which distinguishes between an early stage (phase I), when the processing system identifies
31
word-category information (e.g. determiner [DET], noun [N], verb[V] etc.), phase II at
which point syntactic dependencies and other aspects of morpho-syntactic structure are
computed, and a late phase III that comprises of sentence-level integration and reanalysis
processes. According to Friederici (2002), results from event-related brain potentials (ERPs)
indicate that each stage is associated with a distinct ERP component, phase I with the so-
called Early Anterior Negativity (ELAN) between 150 and 200 ms after stimulus onset for
rapidly detectable word-category violations, phase II with a Left Anterior Negativity (LAN)
between 300 and 500 ms for other kinds of morphosyntactic error, and phase III with a late
positivity (P600) around 600 ms after stimulus onset for syntactic anomalies such as garden-
path sentences that require syntactic reanalysis. In addition, Grodzinsky & Friederici (2006)
identified selective activations of different cortical areas for these stages of sentence
processing by using data from neuroimaging studies. Extending this model to the domain of
morphology, one would expect that violations of the Category Constraint (against inflected
words) are rapidly detected at an early stage of processing and that violations of the Structure
Constraint (against regular inflections) are recognized later. Our results confirm this
prediction and suggest that the processing of a derived form involves two distinct stages, an
initial stage when the derivational affix is stripped off, yielding a simple [[base]+affix]
structure, and a later stage in which the internal structure of the base is analyzed. The
Category Constraint appears to affect the initial stage of processing derived words, whereas
violations of the Structure Constraint are detected later, once the internal structure of the
base has been analyzed.
The proposed account of the eye-movement data hinges on the claim that the dispreference
of regular and irregular plural forms inside derivations is due to the morphological category
of these forms and that regular and irregular plural forms are inflected words rather
uninflected bases. Alternatively, however, we may say that the contrast between singular and
32
plural forms inside derivations is due to the same semantic constraint (against plural
meaning) that has been proposed for compounds (Haskell et al. 2003). Clearly, the effect of
this semantic constraint would be identical to that of our Category Constraint, in that both
constraints prevent regular and irregular plural forms from occurring inside compounds or
derived forms. Whilst it is indeed difficult to distinguish between effects of these two
constraints in English (due to the fact that a singular noun is identical in form to an
uninflected base), we argued that, due to linguistic differences between compounding and
derivation, the semantic constraint does not apply to derivational forms (see section 4
above). For example, the kinds of derivational affixes we tested do not have referents, and
the base of a derived word does not constitute a ‘modifier’. Hence, a constraint that specifies
the semantic relationship between the modifier and the head of a compound does not apply
to derived words. Instead, derivational affixes are subject to selectional restrictions, and the
Category Constraint captures one such restriction, namely that inflected words should not
feed derivational processes.
Further experimental research is needed to determine whether the findings from the eye-
movement experiment reported above can be replicated and the suggested interpretation be
maintained. It would also be useful to examine the processing of derivational forms and their
interaction with inflectional processes in languages in which it is possible to distinguish
more clearly between inflected singular forms and uninflected bases than in English. Another
promising avenue for further research would be to employ the ERP methodology for
investigating these kinds of phenomena. Like eye-movement monitoring, ERPs provide
excellent measures of the time-course of language processing. In addition, distinct ERP
effects have been found for lexical-semantic violations (N400) and morpho-syntactic
violations (ELAN, LAN P600). Thus, data from ERP experiments may provide crucial
33
evidence on how different types of information affect the on-line processing of derivational
forms and other morphologically complex words.
6. Conclusion
The two experiments reported in the present paper each revealed a preference for derived
words containing singular base nouns. In Experiment 1 (as well as in the pre-test of the
materials for experiment 2), derived words containing plural bases received lower
acceptability ratings than derived words containing singular bases. Moreover, in Experiment
2, derived words containing plurals received, for example, longer total viewing times than
those containing singular bases. These findings can be interpreted as resulting from a
constraint of derived word formation (labeled the Category Constraint) according to which
inflected words are dispreferred inside derivational forms. Additionally, the two experiments
revealed that regular plurals are less acceptable than irregular plurals inside derived words.
Derived words containing regular plural bases received lower acceptability ratings than those
containing irregular plurals in Experiment 1, and derived words containing regular plurals
received, for example, longer total viewing times than those containing irregular plurals in
Experiment 2. The results of Experiment 1 (see ‘item set 2’) confirmed that the dissociation
between regular and irregular plurals inside derived words cannot be explained in
phonological terms. Instead, these findings were interpreted as resulting from a
morphological constraint (labeled the Structure Constraint) that prevents regularly inflected
forms (which are morphologically structured and decomposable) from feeding any further
word-formation processes.
We found that these two constraints have distinct time-courses during morphological
processing. The two first-pass measures examined in Experiment 2 (First fixation durations,
gaze duration) showed that derived words containing either regular or irregular plural base
34
nouns had equally longer reading times than derived words containing singular nouns,
indicating that violations of the Category Constraint have an immediate effect on processing.
The later measures, on the other hand, revealed a contrast between regular and irregular
plurals. Derived words containing regular plurals had longer rereading times and longer total
viewing times than derived words containing irregular plurals, indicating that violations of
the Structure Constraint are recognized later. Taken together, these findings are compatible
with stage-based models of language processing and specifically with the hypothesis that
category information is processed earlier than other aspects of morpho-syntactic structure
(Friederici 2002, Grodzinsky & Friederici 2006).
Acknowledgements
Supported by an ESRC postgraduate training scholarship. We are grateful to Iris Berent,
Keith Rayner, the editors of The Mental Lexicon, and the members of the Psycholinguistics
Research Group at our department for comments and helpful discussion.
35
Footnotes
1 Concreteness and familiarity ratings were collected for the singular forms of each noun,
as the MRC database did not provide this information for the plural forms. Concreteness
and familiarity ratings were not available for the singular forms of two items in the
irregular plural condition (louse and goose), nor was a concreteness rating available for
the singular form of one item in the regular plural condition (son).
2 Lexical decision and naming latencies were available for all items except the regular
plural noun mites.
Table 1: Mean acceptability ratings (and standard deviations) for derived forms
Item Set 1 Item Set 2
IRREGULAR REGULAR phon/SIM phon./DIS
singular 5.15 (1.22) 5.07 (1.12 5.08 (1.02) 5.07 (1.09)
plural 4.12 (1.35) 2.87 (1.23)
37
Table 2: Mean durations (and standard deviations) of five reading time measures for the pre-
target region
Irregular Plural Regular Plural Singular
First Fixation Duration 209 (23) 209 (28) 209 (25)
Gaze Duration 233 (39) 238 (47) 229 (36)
Regression Path Duration 288 (73) 308 (114) 308 (79)
Rereading Time 79 (54) 94 (54) 90 (64)
Total Viewing Time 312 (71) 331 (88) 319 (82)
38
Table 3: Mean durations (and standard deviations) of five reading time measures for the
derived word region
Irregular Plural Regular Plural Singular
First Fixation Duration 258 (35) 255 (52) 237 (42)
Gaze Duration 366 (120) 363 (137) 297 (90)
Regression Path Duration 423 (124) 467 (186) 389 (114)
Rereading Time 126 (81) 224 (168) 120 (81)
Total Viewing Time 492 (131) 587 (210) 417 (143)
Appendix A: Frequencies and length of base nouns used in Item Set 1 of Experiment 1
Irregular Regular
Frequency Letters Syllables
Frequency Letters Syllables
Louse 1 5 1 Flea 4 4 1
Ox 4 2 1 Pig 43 3 1
Goose 6 5 1 Duck 14 4 1
Mouse 8 5 1 Rat 24 3 1
Tooth 13 5 1 Eye 523 3 1
Foot 98 4 1 Hand 724 4 1
Woman 338 5 2 Sister 114 6 2
Child 426 5 1 Baby 258 4 2
Man 975 3 1 Brother 138 7 2
Average 207.67 4.33 1.11 204.67 4.22 1.33
40
Appendix B: Frequencies and length of base nouns used in Item Set 2 of Experiment 1
Phonologically Similar Phonologically Dissimilar
Frequency Letters Syllables
Frequency Letters Syllables
Box 102 3 1 Crate 6 4 1
Axe 9 3 1 Spear 12 3 1
Fox 15 3 1 Wolf 10 4 1
Prize 26 5 1 Award 17 3 2
Rose 21 4 1 Daisy 32 3 2
Blouse 11 6 1 Hat 68 4 1
Maize 6 5 1 Corn 24 6 1
Nose 81 4 1 Ear 88 4 1
Average 33.88 4.13 1.00 32.13 4.25 1.25
Appendix C: Frequencies and length of base nouns used in Experiment 2
Irregular Plural Regular Plural Singular
Frequency Letters Syllables
Frequency Letters Syllables
Frequency Letters Syllables
Lice 2 4 1 Mites 2 5 1 Flea 4 4 1
Oxen 2 4 2 Animals 260 7 3 Horse 132 5 1
Geese 5 5 1 Birds 103 5 1 Fish 163 4 1
Mice 10 4 1 Cats 67 4 1 Dog 115 3 1
Teeth 75 5 1 Eyes 523 4 1 Face 460 4 1
Feet 229 4 1 Arms 210 4 1 Hand 724 4 1
Women 511 5 2 Girls 438 5 1 Lady 112 4 2
Children 655 8 2 Boys 349 4 1 Baby 258 4 2
Men 655 3 1 Sons 206 4 1 Husband 154 7 2
Average 238.22 4.67 1.33 239.78 4.67 1.22 235.78 4.33 1.33
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