basden basden 1996
TRANSCRIPT
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retrieval inhibition as an additional mechanism, but did not tie it to a specific
method. We have argued (Basden et al., 1994; Basden, B asden, & Gargano,
1993) that different mechanisms are responsible for directed forgetting with the
two methods, but we have proposed that retrieval inhibition underlies directed
forgetting with the list method, and that differential processing of Remember
and Forget targets underlies directed forgetting with the item method. Inaddition, we have assumed that relational (organisation) processing occurs to a
greater extent with the list method than with the item method, and that item-
specific processing occurs to a greater extent with the item method than with the
list method. In a com prehensive review of the directed forgetting literature,
Johnson (1994) drew a similar conclusion. She attributed greater recall of
Remember than of Forget targets with the list method to segregation and
selective search of each list of targets followed by inhibition of the to-be-
forgotten list. With the item method, segregation and retrieval inhibition are not
required because only the set of Remember targets is stored and searched.
Three lines of evidence support the position that retrieval inhibition occurs
with the list method and not with the item method. First, the item method
typically yields greater directed forgetting than the list method on recall tests, a
result that should be expected if Forget targets are more extensively processed
with the list method than with the item method. Second, the item method yields
directed forgetting on recognition tests, but the list method does not. If items are
less well processed at storage (as we believe is the case with the item method),
recognition memory should be affected. If a set of equally well-processed items
is inhibited from retrieval (as we believe in the case of the list method), a test
that de-emphasises retrieval should be unaffected. Third, the re-presentation of
targets on a recognition test seems to effect a ``release from inhibition on a
subsequent recall test when the list method is used, but not when the item
method is used1
(e.g. Basden et al., 1993; Bjork, 1989). Re-presentation of both
Remember and Forget items would not be expected to eliminate a processingdeficit for the Forget items, but might very well overcome retrieval inhibition.
According to this distinction between relational and item-specific processing
(Einstein & Hunt, 1980; Hunt & Einstein, 1981), procedures that focus the
subjects attention on the list as a whole (or at least on large sections of it)
encourage the identification of relationships among the i tems, whereas
procedures that focus the subjects attention on individual items emphasise
information that is item-specific. T hus, the list m ethod of directed forgetting
w o uld e nc our ag e r ela ti on a l p roc e ssi ng w he re as th e it em m e th od w ou ldencourage item-specific processing. This is not to say, of course, that either
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suggesting that the mix of relational and item-specific information is influence
by the method of directed forgetting. Relational processing should facilitate lis
method directed forgetting because in this case suppression of an entire, alread
processed list must occur. Item-specific processing should facilitate ite
method directed forgetting because in this case individual targets must b
forgotten at the time they are undergoing processing.If the item method encourages item-specific processing and the list metho
encourages relational processing, and if directed forgetting results from
processing deficit with the item method and from retrieval inhibition with th
list method, then factors that enhance item-specific processing should increa
the magnitude of directed forgetting with the item method, and factors th
enhance relational processing should increase directed forgetting with the li
method. In Experiment 1, we manipulated the study format as a means
encouraging either relational or item-specific processing. Our expectation w
that the relative magnitude of directed forgetting with the two methods wou
vary with study format.
E X P E R IM E N T 1
In this experiment one group of subjects attempted to memorise a set of anim
pictures and two other groups of subjects attempted to memorise a list of nam
for those pictures. The subjects in one of the two latter groups w ere given simp
learning instructions and those in the other group were told to form a ment
image of the referent of each target. A few prior studies have employed imag
or pictures in the context of directed forgetting (Bray, Justice, & Zahm, 198
Bugelski, 1970). Unfortunately, no firm conclusions could be drawn from the
previous studies.
According to Hunt and his colleagues, item-specific processing is encourage
either by forming images of the targets (Hunt & Marschark, 1989) or bstudying pictures corresponding to the targets (Hunt & McDaniel, 1993). Hu
and McDaniel have also argued that simple presentation of a categorised list f
learning encourages relational processing. As mentioned earlier, item-metho
directed forgetting is usually greater than list-method directed forgettin
According to our analysis, this difference in the m agnitude of directed forgettin
should be greater when subjects study pictures or study words with image
instructions that when they study words alone, particularly when the wor
belong to a single category.One interpretation of directed forgetting is that contextual information abo
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retrieval inhibition. Unfortunately, a potential source of confounding is present
if subjects base their judgements of list membership on item strength. If this
were the case, judgements of list membership might not reflect context
information alone. A more direct measure of memory for context information is
to have subjects indicate the approximate serial position of previously recalled
targets. Tzeng, Lee, and Wetzel (1979) introduced this technique. With the itemmethod they found that serial position information was remembered better for
Remember than for Forget targets. No control subjects were tested, so no
absolute assessments were possible.
The results of Tzeng et al. are equally consistent with the idea that Forget
items are less extensively processed with the item method. If Remember and
Forget targets are equally well processed with the list method, then accuracy of
serial position information should be equivalent for the Forget and Remember
items with this method. However, if Geiselman et al. are correct and context
memory is reduced by directed forgetting instructions, then memory for serial
position of F orget targets should be affected with both the item and the list
methods.
In this experiment we asked our subjects to indicate approximate serial
positions for the items they recalled. To determ ine the influence of directed
forgetting instructions on absolute memory for contextual information, we
included control subjects who did not receive directed forgetting instructions. If
contextual information is lost during directed forgetting, then memory for serial
position should be less accurate for Forget targets in the experimental conditions
than in the control conditions.
Although control subjects were included to permit measurement of absolute
loss of contextual informa tion, their inclusion also permitted us to com pare the
absolute effects of directed forgetting instructions on Remember and Forget
targets for each of the two methods. Past research has shown that directed
forgetting instructions yield not only lower recall of Forget targets, but alsogreater recall of Remember targets (see Bjork, 1972).
Method
Subjects. We tested 194 students enrolled in introductory psychology
classes at California State University, Fresno. Their participation was in partial
fulfilment of course requirements. Approximately 22 subjects were tested in
each of the nine treatment conditions.
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was designated Forget and Remember equally often across groups. Order w
varied across groups to ensure that particular targets did not consistently occup
favourable serial positions across m ethods. Subjects responded by writing the
recall on lined pages included in their response booklets.
Design. A 3 2 2 mixed factorial design was employed with studformat (pictures, words with imagery instructions, or words without image
instructions) and method ( list or i tem) as between-subjects factors an
instruction (Remember or Forget) as a within-subject factor. Three outsid
control groups were also tested, one with each of the three study format
Subjects in these groups were not given directed forgetting instructions.
Procedure. Groups of up to six subjects at a time were assigned to testin
conditions in accordance with a block-randomisation schedule. Subjects we
given instructions appropriate to their study format prior to target presentatio
For the image study format, subjects were instructed to form an image of eac
word as it was presented to them. For the picture and word study format
subjects were simply instructed to do their best to recall all targets. A blan
screen or a spot of l ight of 1.1 second duration followed each target for a
subjects. Subjects tested with the item method were given the followin
additional instructions:
After each item has been on the screen for a few seconds, it will be followed by a
blank screen or a spot of light. A blank screen means you are to forget that item but
a spot of light means you are to remember that item.
Subjects tested by the list method were not told to differentiate among items an
were told to ignore the presence or absence of lights.
After subjects had read the initial instructions, they were shown the words pictures individually at a three-second rate. After the first 12 targets had bee
presented, subjects tested by the item method were told to rest for a few second
Subjects tested by the list method were given directed forgetting instructions f
the first list. Thus, the time interval between list halves was equivalent for th
two methods. Then the remaining 12 targets were presented.
Target presentation was im media tely followed by a distractor task intended
purge short-term memory. Subjects com pleted simple arithmetic problems
their response booklets for 30 seconds; then they were instructed to write many of the targets they had studied as they could remember, including both th
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through to ``6 if it occurred among the last four targets (cf Tzeng et al., 1979).
After the experiment was over, the subjects were told the purpose of the forget
instruction and were asked not to discuss the experiment with other potential
subjects.
Results
The dependent variable in free recall was the proportion of Remember or Forget
targets recalled. For control subjects, targets that occupied the same serial
positions as actual Remember and Forget targets in the experimental conditions
were designated nominal Remember and Forget targets. Thus, determination of
nominal Remember and Forget targets for individual control subjects depended
on whether the comparison was with list method or item method experimental
subjects. Mean recall proportions for each of the conditions are shown in Table 1.
A mixed three-factor analysis of variance was performed with method and
study format as between-subjects factors and instruction as a repeated measure.
The three-factor interaction was significant, F(2, 127) = 3.53, M Se = 0.036.
Subsequent analysis revealed that the simple interaction between method and
instruction was significant for pictures, F(1, 42) = 4.21, MSe = 0.032; and for
words with images, F(1, 45) = 14.89, M Se = 0.027, but was not significant for
words w ithout images, F
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M Se = 0.037, for words with images, F(1, 22) = 95.86, M Se = 0.022, and f
words without images, F(1, 19) = 15.62, M Se = 0.043. With the list m ethod, th
magnitude of directed forgetting was also statistically significant for all thr
study formats: for pictures, F(1, 21) = 12.47, M Se = 0.038, for words wi
images, F(1, 23) = 11.12, MSe = 0.031, and for words without images, F(
21) = 20.45, MSe = 0.048.
As mentioned earlier, we compared the list method and item method directe
forgetting subjects with the same control subjects. This necessitated separa
three-factor analyses of variance for each method, with study format and grou
(experimental vs. control) as between-subjects factors and instruction as
repeated measures factor. For the item method analysis, the effect of stud
format was significant, F(2, 120) = 7.77, MSe = 0.035. Images were recall
better than pictures or words. The interaction between instruction and group w
significant, F(1, 120) = 65.21. Tests of simple effects confirmed that recall
Remember targets was greater for experimental than for control subjects, F(
120) = 13.04, M Se = 0 .158 ; b ut rec all of Fo rg et t arg ets w a s poo re r f
experimental than for control subjects F(1 120) = 46 06 MSe = 0 1922
F
FIG. 1. Magnitude of directed forgetting as a function of study format and instruction.
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the list method analysis, the interaction between group type and instruction was
again significant, F(1, 123) = 27.87. As in the analysis of the item method, recall
of Remember targets was greater for experimental than for control subjects, F(1,
123 ) = 8.03, M Se = 0 .2 01; bu t r eca ll of F or ge t ta rge ts w as p oo re r f or
experimental than for control subjects, F(1, 123) = 17.75, M Se = 0.017.
An analysis conducted on the proportion of correct serial position placementsfor the item method yielded a significant main effect for instruction, F(1,
60) = 5.64, M Se = 0.054. The proportion of correct placements was 0.50 for
Remember targets and 0.40 for Forget targets. A similar analysis for the list
m ethod yielded no significant effects, the mean propor tion of c orrect placements
was 0.42 for Remember targets and 0.48 for Forget targets.
An analysis was conducted on the proportion of correct serial position
placements of Forget i tems contrasting directed forgetting subjects with
controls. Subjects placed Forget targets equally accurately in the experimental
and control conditions, Fs < 1. This held true for both the item and list methods.
Discussion
W e have hypothesised that study formats encouraging item-specific processing
would increase directed forgetting m ore with the item method than with the list
m ethod. This hypothe sis was confirmed . The difference in magnitude of directed
forgetting with the item and list methods was greater when subjects studied
pictures or words for which they formed images than when they simply studied
words. Directed forgetting was actually equivalent for the two methods when
subjects studied words w ithout forming images. The se results are consistent with
our distinction between item and list methods, i.e. that relational processing
underlies directed forgetting with the list method, but that item-specific
processing underlies directed forgetting with the item method.
The present results are not consistent with those of Bugelski (1970), whoreported an absence of directed forgetting with the item method when subjects
were asked to form images of the targets they studied. His report is quite sketchy
with regard to procedures, but we assume that they differed from our own in
some important way. Our results are consistent with those of Bray and his
colleagues, e.g. Bray et al. (1983). These investigators reported robust directed
forgetting when subjects studied pictures.
Bugelski had argued, on the basis of his failure to find directed forgetting,
that subjects could not inhibit targets for which they had formed images. On thebasis of our own results we would argue that subjects did not carry out extensive
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Remember items. In the present study this occurred with both the list and ite
methods. Recall was poorer for Forget targets and better for Remember targe
as compared with controls. Bjork (1970) has argued that Remember targets a
subject to less interference in the experimental conditions. This argument cou
be applied to either method of directed forgetting.
If differential processing underlies item-method forgetting, then seriposition information should be better for Remember than for Forget items wi
this method. If differential processing is not responsible for list-method directe
forgetting, then serial position information should be the same for Rememb
and Forget items with this method. As predicted, memory for serial positio
information was better for Remember than for Forget i tems with the ite
method, but not with the list method. These results support our position.
To test the hypothesis expressed by Geiselman et al. (1983) that direct
forgetting occurs when subjects lose access to contextual information, w
compared accuracy of serial position information for Forget targets in th
experimental and control conditions. Although Geiselman et al. reported th
memory for list membership of Forget items was greater for control than fo
experimental subjects, we found no corresponding difference in the accuracy
memory for serial position. Furthermore, our results were quite similar with th
list and item methods. Thus, our results do not support the hypothesis th
directed forgetting results from loss of contextual inform ation. O f course, a qui
different picture might emerge if recollection for serial position of all items ha
been assessed.
Thus, results of Experiment 1 were consistent with the hypothesis th
retrieval inhibition and relational processing underlie directed forgetting wi
the list method, but that differential item-specific processing underlies directe
forgetting with the item method. In Experiment 2, we compared the influence
the list- and item-m ethod directed forgetting on performance in an impli
memory test. Current research and reviews (e.g. Brown & Mitchell, 199 Thapar & Greene, 1994) indicate that levels of processing manipulations ma
influence priming on implicit tests. If, as we suggest, R emember targets a
more extensively processed than Forget targets with the item method, then item
method directed forgetting may occur on implicit tests but list-method direct
forgetting should not.
E X P E R IM E N T 2
Directed forgetting on implicit tests has sometimes been observed with the ite
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(e.g. word fragment cued recall, stem-cued recall, recognition, and word
association) do not produce list-method directed forgetting (see Basden et al.,
1993). List-method directed forgetting instructions appear to act on the list as a
whole rather than on individual items.
In previous experiments that obtained item-method directed forgetting on
implicit tests (e.g. MacLeod, 1989), perceptual tests such as word fragmentcompletion were used. Such tests are typically less sensitive to differential
processing (see Roediger & McDermott, 1993) than are conceptual tests (tests
relying on meaning). Thus, demonstrations of item-method directed forgetting
should be easier to obtain on implicit conceptual tests. In research reported
earlier we failed to observe item-method directed forgetting with an implicit
word association test (Basden et al., 1993, Experiments 1 & 2). However, this
failure may have resulted from a floor effect, as priming was not statistically
significant with the conceptual test we used. The present experiment represents
another attempt to obtain item-method directed forgetting with an implicit
conceptual test. The list method was included for purposes of comparison.
After studying a list of low-frequency words with either item- or list-method
directed forgetting instructions, the subjects were given an implicit test of
general knowledge. Definitions of targets and distractors were provided at the
time of the test, and subjects were instructed to respond to each of them with the
first word that came to mind. Low-frequency words were used because such
materials typically yield higher levels of priming than do high-frequency words
(Roediger & McDermott, 1993). As this test, like other implicit tests, includes
item-by-item cueing, i t should be sensit ive to differential processing of
Reme mber and Forget items of the sort we believe the item method encourages.
Therefore, we expected directed forgetting w ith the item method but not with the
list method.
After completing the implicit general knowledge test, subjects were asked to
free recall the Remember and Forget targets. We expected directed forgettingwith the list method as well as with the item method on this test, because free
recall is sensitive to the retrieval inhibition we believe occurs with the list
method. We expected greater directed forgetting with the item method than with
the list method as in our previous research.
Method
Subjects. We initially tested 68 subjects and later added 69 more subjects.We also tested 28 similar subjects in a pilot study used to assess the materials.
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Dictionary. The materials were then piloted to confirm that prospective subjec
could match the words with their definitions. These definitions were used
prepare a test of general knowledge.
All materials were presented using a microcomputer. The subjects typed the
responses at the computer keyboard.
Design. We employed a mixed two-factor design with method (item or lis
as a between-subjects factor and instruction (Forget or R emember) as a withi
subject factor. The dependent measure was the number of experimente
designated terms produced on the test of general knowledge and on th
subsequent free recall test.
Procedure. Subjects were assigned to the method of directed forgetting
accordance with a block-randomisation schedule. After entering the conditio
code at the computer keyboard, the experimenter left the test cubicle; th
remainder of the procedure was automatically administered. The programm
randomly selected a study list of 48 targets and 48 distractors from the corpus
192 words. The 48 list members were randomly separated into 24 Rememb
and 24 Forget targets. Individual random presentation and testing orders we
also program-generated. Prior to list presentation all subjects w ere informed th
their ability to remem ber list membe rs would be tested later. Subjects tested wi
the item method were also given the following instructions:
After each word has been on the screen for a few seconds, a brief signal will tell
you whether to REMEMBER it or FORGET it. If the signal is REMEMBER you
should be prepared to recall the word later, but if the signal is FORGET you can
forget the word.
After reading these initial instructions, all subjects were shown the targeindividually at a six-second rate. For subjects tested with the item metho
``REMEM BER or ``FORGET joined each item during its final three secon
of exposure. After the first 24 targets had been presented, subjects tested wi
the item method w ere told to rest for a few seconds and subjects tested with th
list method were given the following directed forgetting instructions:
The list you have just studied was only for practice. You can forget it now. The list
you will see next is the one we want you to remember, so forget the practice listand concentrate on this new list.
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thought was associated with each commodity on the screen, e.g. ``Georgia for
PEACHES. Subjects continued with this task until they had responded to all
commodities or until 30 seconds had elapsed without a response.
Subjects were told that the general knowledge test, which immediately
followed the distractor task, was part of a different experiment. The definitions
corresponding to the 48 targets and 48 distractors were displayed individually inrandom order. The subjects were instructed to type the first appropriate w ord
that came to mind for each definition. The next definition appeared immediately
after the subjects response to the previous one, or after 30 seconds in any case.
After the subjects had completed the general knowledge test, they were given
a free recall test. Subjects typed their recall on the computer keyboard,
continuing until 30 seconds had elapsed without additional recall.
Results
A preliminary analysis revealed no differences in results for the initial and
subsequently added subjects, so the two data sets were combined for the analysis
reported here.
Priming Scores. The dependent variable was the proportion of designated
terms (Remember targets, Forget targets, and distractors) that were produced in
response to their definitions on the general know ledge test. Mean proportions foreach group are shown in Table 2.
We performed a two-factor mixed analysis of variance on the proportions of
target words produced on the general knowledge test. More targets were given
with the list method than with the item method, F(1, 135) = 11.33, MSe = 0.03;
a nd m or e ta rge ts w er e g ive n t o d efi niti ons o f R em em be r w ords th an to
definitions of Forget words, F(1, 135) = 20.33, M Se = 0.007. The interaction was
also significant, F(1, 135) = 6.82. Simple tests established that directed
f or ge tt in g w a s s ig ni fi ca nt w ith t he ite m m e th od , F( 1 , 6 7 ) = 2 2 . 80 ,
M Se = 0.008, but not with the list method, F(1, 68) = 2.02, M Se = 0.007.
To determine whether priming had occurred, the proportions of Remember
and Forget targets provided were individually compared with the proportion of
T A B L E 2
Mean Proportions of Remember, Forget, and Distractor Terms Produced on the General
K n o w l e d g e T e s t i n E x p e r i m e n t 2
Word Type
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d is tr a ct o rs p r ov id e d . R e m e m b e r- ta r ge t p r im i n g w a s si g ni fic a n t, F(
135) = 239.40, M Se = 0.007. The interaction with method was significant, F(
135) = 5.20, reflecting greater priming with the list method than with the ite
method. Simple tests confirmed significant priming of Remember targets wi
both the list method, F(1, 68) = 159.18, M Se = 0.007, and the item method, F(
67) = 86.15, MSe = 0.007.The results of the Forget-target priming analysis were similar to those for th
Remember-target priming analysis. Both the effect of method, F(1, 135) = 8.2
M Se = 0.006, and the effect of instruction, F (1, 135) = 137.48, w ere significan
The significant interaction, F(1, 135) = 29.47, again reflected greater primin
with the list m ethod than with the item method. Simple tests confirmed th
Forget-target priming was significant for both the list method, F(1,68) = 149.5
M Se = 0.006, and the item method, F(1, 67) = 19.51. Thus, both Remember an
Forget words showed significant priming with both methods, but priming w
greater with the list method than with the item method.
F r ee R e c a ll . A tw o- fa cto r m i xe d m o de l a na ly sis of v arianc e w
performed on the proportions of Remember and Forget words produced durin
the final free recall test. Mean recall proportions for Remember and Forg
words were 0.14 and 0.11 with the list method, and 0.17 and 0.06 with the ite
method. The effect of instruction w as significant, F(1,134) = 60.53, M Se = 0.00
The interaction was also significant, F(1, 134) = 24.32, MSe = 0.005, reflectin
greater directed forgetting with the item method than with the list metho
Directed forgetting was significant with both the item method, F (1,67) = 75.5
M Se = 0.006, and the list method, F(1, 67) = 4.36, MSe = 0.005.
Discussion
Earlier we reported our failure to obtain item-method directed forgetting on aimplicit word association test (Basden et al., 1993, Experiments 1 & 2). W
attributed that null result to the low levels of priming that were observed. Th
experiment was designed to provide a more adequate test of directed forgettin
on a conceptual implicit test; i.e. one that showed adequate priming. We we
successful in that priming on the general knowledge test was significant for bo
Remember and Forget words and with both methods. There are several reaso
for greater priming in the present experiment. First, we used more targets, thu
permitting more observations. Second, the general know ledge items were relatively low frequency. Third, more redintegrative information is provided b
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confirmed. Thus, i tem-method directed forgetting occurred on both the
conceptual test and on the explicit free recall test, but list-method directed
forgetting occurred only on the latter. These results are consistent with our
hypotheses that (a) Remember targets are more extensively processed than
Forget targets with the item method but not with the list method, and (b) tests of
implicit memory are sensitive to the effects of differential processing but not to those of retrieval inhibition. When subjects are given retrieval cues on an item-
by-item basis, suppression of the entire Forget list is unlikely to occur.
G ol di ng , L o ng a nd M a cl eo d ( 199 4) ha ve s ug ge st ed th at, as d ir ec te d
forgetting instructions may result in differential processing of Remember and
Forget words, the underlying basis for directed forgetting on implicit tests may
be differential levels of processing, much as w e have suggested here. However,
they did not distinguish between item- and list-method directed forgetting. If
differential processing underlies directed forgetting with both the list and item
method, then the list method should yield directed forgetting on implicit tests.
Not only should it occur, it should be greater than with the item method. In
mixed-list designs, investigators have found that the levels of processing effect
is larger when targets are blocked at presentation as in the list method rather than
random ly intermingled as in the item method (Challis & Brodbeck, 1992;
Thapar & Greene, 1994). The fact that this does not occur makes it clear that
differential processing of Remember and Forget items is not responsible for list-
method directed forgetting.
It could be argued that directed forgetting on item-method implicit tests
results from contamination of a supposedly pure test of automatic processing by
intentional retrieval. Toth, Reingold, & Jacoby (1994) recently applied the
process dissociation procedure to levels of processing findings. They reported
that conscious recollection accounted for the advantage of semantically
processed targets relative to nonsemantically processed targets on implicit
tests. Previously, item-method directed forgetting has been observed whensubjects were told to engage in intentional retrieval (Basden et al., 1993,
Experiment 3) or when the implicit test was not well camouflaged (MacLeod,
1989). Russo and Andrade (1995) recently applied the process dissociation
procedure to word fragment completion data that showed a directed forgetting
effect with the inclusion test procedure. Their estimate of the contribution of
conscious recollection was greater for Rem ember than for Forget targets. Their
results are consistent with our argument (Basden et al., 1993) that intentional
retrieval may contribute to directed forgetting on implicit tests. However, aninclusion test encourages subjects to consciously recollect the target items,
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taken to reduce the likelihood of contamination by intentional retrieval
s ugg e st ed b y R oe d ig er a nd M c D e rm o tt (1 99 3) . A pp l ic at io n o f p ro ce
dissociation procedures to properly conducted implicit tests may be gratuitou
In Experiment 3, we provided a further test of our contention that item
method directed forgetting involves differential processing but list-metho
directed forgetting does not. If Remember words are more extensively processe than Forget words with the item method but not with the list method, directe
forgetting should be absent when only the familiarity of Remember and Forg
items is assessed.
E X P E R IM E N T 3
In this experiment we turned to the distinction between Know and Recolle
judgements presented by Tulving (1985) and developed extensively by Gardin(e.g. Gardiner, 1988; Gardiner & Java, 1993).
3Such judgements partitio
recognit ion performance into two components, one reflecting conscio
recollection (Recollect judgements), and the other reflecting familiarity (Kno
judgements). Recollect and Know judgements are obtained by asking subjects
indicate for each recognised item whether its actual occurrence in the study li
is remembered or it merely seems familiar.
Gardiner (1988, Experiment 1) observed a levels of processing effect wi
Recollect judgements but not with Know judgeme nts. Gardiner, Gawlik, an Richardson-Klavehn (1994) found i tem-method directed forgetting w
Recollect but not with Know judgements. In the present experiment w
included both methods of directed forgett ing. If, as we have propose
Remember and Forget targets are differentially processed with the item metho
but not the list m ethod, then directed forgetting should occur with Recolle
judgements for the item method but not for the list method. Neither method w
expected to yield directed forgetting with Know judgements.
M e t h o d .
Subjects, Materials, and Apparatus. We tested 40 students of the sam
description as in our earlier experiments. The word list and apparatus were th
same as in Experiment 2.
Design. The design w as a 2 2 factorial. Method (item or list) w
manipulated between subjects and instructions (Remember or Forget) wmanipulated within subjects. All subjects were given a recognition judgeme
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Procedure. The study instructions and method of presentation were the
same as in Experiment 2. List presentation was immediately followed by a
recognition judgement test. Instructions were drawn verbatim from Rajaram
(1993). To paraph rase, subjects were told to respond w ith ``N (Not Recognised),
if they did not remem ber having studied any given word; w ith ``K (Know ), if the
word appeared familiar, i.e. if they we re aware of the word in the context of theexperiment, but were unable to recollect any contextual information about that
word; and with ``R (R ecollect) if they consciously recollected having studied
that w ord. Each target or distractor wa s presented in uppercase letters, centred on
the monitor screen. Definitions of the available responses appeared below each
target and distractor. Subjects pressed ``N, ``K, or ``R, on the computer
keyboard for each word. Each new word was presented immediately after a
response to the previous word, or after 30 seconds in any case.
Results
The mean proportions of Remember and Forget words judged as Recollect and
Know are shown in Table 3, along with Recollect and Know judgements for
distractors.
A mixed two-factor analysis of variance was performed on the Recollect
judgements for Remember and Forget targets. I t produced a s ignificant
interaction between method and instruction, F(1, 38) = 11.32, M Se = 0.015.Subsequent simple tests showed directed forgetting with the item method, F(1,
19) = 26.04, M Se = 0.014, but not with the list m ethod, F
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significant, F(1, 38) = 11.54. The difference between Forget and Distract
w ord s w as s ig nifi cant no t o nly w ith th e lis t m e tho d, F(1, 19) = 235.3
M Se = 0.019, but also with the item method, F(1, 19) = 69.17, M Se = 0.028. Th
difference between Forget and Distractor words was greater with the list metho
than with the item methods.
Discussion
In earlier reports (see Basden et al., 1993; Basden et al., 1994), we demonstrate
that directed forgetting occurs in recognition with the item method but not wi
the list method when overall performance is examined. This experime
c onf ir m s th is c onc lu si on , a nd de m o ns tr at es t ha t i t a pp lie s t o R e co ll e
judgements and not to Know judgements. This dissociation supports o
hypothesis that the processes underlying directed forgetting differ for the twmethods. The difference in correct Recollect judgements between Forget an
Distractor items was greater with the list method than with the item method, b
the corresponding difference between Remember and Distractor items was th
same with the two methods. Forget words appear to receive less extensi
processing than Remember words with the item method, but Remember an
Forget words appear to receive equivalent processing with the list method.
Our results with the item method replicated those of Gardiner et al. (1994
They varied the delay of the Forget or Remember cue and found that increasede lay w as a ss oc iate d w it h a n inc rea se in K now judge m en ts fo r item
accompanied by either cue. Increased cue delay was associated with an increa
in Recollect judgements for Remember targets but not for Forget targets. The
interpretation, with which we concur, was that maintenance rehearsal influenc
familiarity, and hence, Know judgements. There is no corresponding increase
Recollect judgements with delay, because elaborative rehearsal is necessary
increase conscious recollection.
The present results are consistent with evidence from Experiment 1 th
subjects retain greater contextual information for Remember than for Forg
words with the item method but not with the list method. Subjects were mo
accurate in providing serial position information for Rem ember than for Forg
targets with the item method than w ith the list method. The ability to rememb
the serial position of targets reflects greater conscious recollection for the
context. Similarly, Recollect judgem ents reflected memory for the specif
context in which particular words occurred. This is consistent with our argume
that the item method is more encouraging to differential processing than is th
list method
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presentation of items from a single category, having subjects study pictures or
form images increased directed forgetting m ore with the item method than with
the list method. In Experiment 2, directed forgetting occurred with the item
method but not with the list method when responses to general knowledge
questions were analysed. In Experiment 3, Recollect judgements showed
directed forgetting w ith the item method but not with the list method. Thus, the present research further confirms that the processes underlying item- and list-
method directed forgetting differ.
The present results should be of interest to those who study inhibitory
mechanisms in recall. Although directed forgetting was greater with the item
method than with the list method when pictures and images (which encourage
item-specific processing) w ere studied, it was equivalent with the two methods
when words alone (which encourage relational processing) were studied. Thus,
for materials that encourage relational processing, the retrieval inhibition
process may yield substantial directed forgetting. Perhaps because directed
forgetting tends to be more reliably obtained with the item method than with
the list method (e.g. Basden et al., 1993), many recent experiments have been
conducted with the item method, particularly when implicit tests were used
(e.g. Gardiner et al., 1994; Golding et al., 1994; MacLeod, 1989; Russo &
Andrade, 1995). This seems an unfortunate choice because, by our account, it
is the list method that reflects subjects ability to lose or regain access to
previously stored information. Understanding of retrieval inhibition in the
context of directed forgetting may facilitate our understanding of retrieval
inhibition in more exotic contexts, such as recovery of repressed memories
(e.g. Cloitre et al., 1995).
Interest in inhibitory mechanisms in memory has enjoyed a recent resurgence
and new theoretical approaches have emerged. Zacks, Radvansky, and Hasher
(1995) presented an approach that distinguishes betw een two different inhibitory
mechanisms in directed forgetting. The first involves retrieval inhibition; thesecond involves the stopping of rehearsal following presentation of a Forget cue.
The latter mechanism is one that prevents information from entering working
memory (see Hasher & Zacks, 1988). According to this formulation older
subjects are deficient in inhibitory processing. Target information that is
designated as to-be-forgotten may not be successfully inhibited, either because
subjects cannot successfully inhibit retrieval of previously stored information or
because items designated as to-be-forgotten are processed just as effectively as
items that are not designated as to-be-forgotten. Experiments conducted byZacks et al. showed that older subjects were less successful in meeting the
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It has been proposed (Geiselman et al., 1983, p.63) that directed forgettin
can be accounted for in terms of a mechanism by which ``an F cue serves
initiate a process that inhibits the accessibility of a space in time in episod
memory. However, when we measured memory for context by asking subjec
to provide serial position information for the Forget items they had recalled, w
found that experimental subjects were as accurate in their judgements as wecontrol subjects. As our measure of contextual memory is less likely to hav
been contaminated by attributional errors than is the measure used by Geiselma
et al., we conclude that there is little evidence to support an explanation
retrieval inhibition in directed forgetting that relies on loss of contextu
information.
In conclusion, our results clearly show the desirability of distinguishin
between the two methods of directed forgetting, as initially proposed by Bjor
(1972). Item-method directed forgetting relies on processing distinctive featur
of individual targets and influences retention of Remember and Forget targets
a manner analogous to levels of processing procedures. On the other hand, lis
method directed forgetting encourages relational processing and appears
differentially influence performance only on a free recall test, a test that
sensitive to relational processing. When subjects are provided with retriev
information in the form of word associates, word fragments, or copy cue
directed forgetting with the list method disappears. Only when subjects a
required to rely on their own organisational system is list-method directe
forgetting manifested. These observations support the idea that list-metho
directed forgetting is dependent on organisational (relational) processin
whereas item-method directed forgetting is dependent on distinctive (item
specific) processing.
Manuscript received 25 May 19
Manuscript accepted 11 December 19
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