c hapter 9. selection of action

고려대학교 산업공학과

IND641 Engineering Psychology

Chapter 9. Selection of Action OVERVIEW

skill-based behavior – the most automated level; a rapid automatic responses with a minimum investment of resources; extensive training and experience

rule-based behavior – action by bringing into WM a hierarchy of rule – less automatic and timely knowledge-based – entirely new problems; neither rule nor automatic mappings exist –

diagnoses, decisions, troubleshooting selection of skill-based actions – response time or reaction time (RT) – simple and choice RT

VARIABLES INFLUENCING BOTH SIMPLE AND CHOICE REACTION TIME stimulus Modality

simple RT to auditory stimulus (130 msec) is faster than visual stimuli (170 msec) Stimulus Intensity

simple RT decreased with increases in intensity of the stimulus to an asymptotic value (Fig 9.1) aggregation over time of evidence in the sensory channel until a criterion is exceeded

temporal Uncertainty the degree of predictability of when the stimulus will occur manipulated by warning interval (WI) between a warning signal and imperative stimulus to

which the person must response short and constant WI imperative stimulus is highly predictable (temporal uncertainty is low)

short RT long or variable WI high temporal uncertainty long RT



Expectancy RT increases as the average WI of a block of trials becomes longer (temporal uncertainty) an opposite effect is observed within a block having randomly varied long and short WIs – the

concept of expectancy VARIABLES INFLUENCING ONLY CHOICE REACTION TIME

The Information Theory Model: The Hick-Hyman Law choice RT was longer than simple RT RT was a negatively accelerating function of the number

of stimulus-response alternatives Hick (1952) and Hyman (1953) applied information theory to quantify the uncertainty of stimulus

events (Fig 9.2) choice RT increased linearly with stimulus information (log2N)

RT = a + bHs (Hick-Hyman law) human has a relatively constant rate of processing info, defined by inverse slope (1/b) (bits/sec)

The Speed-Accuracy Trade-off they tend to make more errors as they try to respond more rapidly bandwidth as Ht/RT (bits/sec) constant bandwidth model of human performance is not quite

accurate Howell and Kreidler (1963, 1964) – easy and complex choice RT tasks by different

instructions – fast, accurate, fast and accurate, maximize H t

instructions changed RT and error rate; speed instruction having the largest effect easy choice RT – max. Ht obtained by maximize Ht instruction complex choice RT – highest level of performance efficiency with speed set instruction



The Speed-Accuracy Operating Characteristic (SAOC) RT is on the x-axis and accuracy (error rate) on the y axis (Fig 9.3) info. transmission (performance efficiency) is optimal at intermediate speed-accuracy sets accuracy (=log[P(correct)/P(errors)]) linear SAOC (Fig 9.4) one important aspect of the speed-accuracy trade-off is its usefulness in deciding what is “best” The Speed-Accuracy Micro-Trade-off compare the accuracy of fast and slow responses within a block of trials, using the same system

(or experimental condition) – depend on the particular nature of the RT task when the criterion is conservative processing full info, taking longer time high accuracy when the criterion is risky response initiated rapidly, based on little evidence errors will be likely in the extreme “fast guess” – a random response initiated as soon as the stimulus is detected

error RTs are faster than correct RTs when RTs are short and stimulus quality is good if poor stimulus, long processing or working memory load – opposite form of micro-trade-off

error responses tend to be slower than correct ones

DEPARTURE FROM INFORMATION THEORY Stimulus Discriminability

RT is lengthened as a set of stimuli are made less discriminable from one another similarity or difference – the ratio of shared features to total features within a stimulus discriminability difficulty reduced by deleting shared and redundant features where possible



The Repetition Effect repetition effect, the advantage of repetitions over alternations, is enhanced by increasing N (the

number of S-R alternatives), by decreasing S-R compatibility, and by shortening the interval between each response and the subsequent stimulus

No repetition effect1. long intervals between stimuli and may be replaced by an alternation effect (faster RT with

a stimulus change) – gambler’s fallacy do not expect a continuous run of the same sort2. rapid repetition of the same finger slower than alternations

Response Factors1. RT is lengthened as the confusability between responses is increased2. RT is lengthened by the complexity of the response

Practice practice decreases the slope of the Hick-Hyman law function relating RT to info compatibility and practice appear to trade off reciprocally in their effect on this slope

Executive Control it takes time to load or activate these rules when they are first used or shift from one to another

the function of central executive control Stimulus-Response Compatibility

Location Compatibility provided by human’s intrinsic tendency to move or orient toward the source of stimulation



colocation principle – controls next to the relevant display – not always possible to achieve (Fig 9.5) congruence – congruence between spatial controls and displays (Fig 9.6); often defined in terms of

an ordered array rule increase from left to right, aft to forward, clockwise, bottom to top far-right to top when left-right array mapped to a vertical display top-down ordering is not strong vertical display (or control) arrays that are not congruent with

control (display) arrays should be used with caution put a slight cant, or angling, of one array in a direction that is congruent with the other (Fig 9.7

) Movement Compatibility the set of expectancies that an operator has about how the display will respond to the control

activity: Cognitive-Response-Stimulus (C-R-S) compatibility congruence principle of location compatibility applied to the compatibility of movement when congruence violated, a common mapping of increase; also governed by a principle of

movement proximity in Fig 9.8 (Warrick principle) -- not related to congruence Compatibility Ambiguities mental model

1. movement proximity principle was far less pronounced for psychology students than ME students, ME having the strong mental model of the mechanical linkage

2. a design for the vertical speed of an aircraft (Fig 9.9)3. frame or reference -- exocentric viewpoint (compatible S-R movement), egocentric viewpoint4. distinction between status and command displays



Transformations and Population Stereotypes any S-R mapping that requires some transformation will be reduced in its compatibility population stereotypes define mappings that are more directly related to experience Consistency and Training be wary of possible violation of consistency to optimize the compatibility of each training can also be used to formulate correct mental model and enhance the agreement

between the mental model and the correct dynamics Knowledge in the World should provide an invitation to the appropriate actions (affordance) or forcing function, as

well as a “lockout” of the inappropriate actions (Fig 9.5 and Fig 9.10) STAGES IN REACTION TIME

The Subtractive Method delete a mental operation entirely form the RT task – the decrease in RT is assumed to

reflect the time required to perform the absent operation Additive Factors Technique

confirming evidence for the existence and identity of processing stages (Fig 9.11) to define the existence and distinctiveness of different stages by manipulating variables

that are known to lengthen reaction time interactive (influence a common stage of processing); additive (influence different stages) Experimental Techniques

make inferences about what manipulations influence what stages of processing patterns of additivity and interactions (Fig 9.12)



1. the response selection is a major bottleneck in speeded information processing2. stimulus probability appears to affect two stages

1. improbable stimuli require longer to be recognized2. their associated responses take longer to be selected

Applications of Additive Factors Methodology how information processing speed is influenced by aging, poisoning, mental workload Problems With Additive Factors the assumption that stages proceed strictly in series convincing evidence that information

processing does not strictly proceed in a serial fashion underadditive relationship – delay by increasing the difficulty at one stage of processing is

actually smaller at the more difficult level of the other stage The Event-Related Brain Potential as an Index of Mental Chronometry

event-related brain potential (ERP) a direct estimate of the timing of processes up to the intermediate stage of stimulus

categorization – a series of electric voltage from the surface of the scalp The Value of Stages

the separation of processing stages should not taken too literally some overlap in time between processing in successive stages – parallel processing the stage concept more than compensates for any limitations in its complete accuracy

SERIAL RESPONSES The Psychological Refractory Period

PRP – a situation in which two RT tasks are presented close together in time



ISI (interstimulus interval) – the separation in time between the two stimuli – SOA the second stimulus response is delayed by the processing of the first under short ISI human being as a single-channel processor of information

the processing of S1 temporarily captures the single-channel bottleneck S2 must wait until S1 is finished anything that prolongs the processing of S1 will increase the PRP delay of RT2 in Fig 9.14 (simple reaction vs. choice reaction)

perceptual analysis of S2 can proceed even as the processor is fully occupied the delay in RT2 will increase linearly with a decrease in ISI and with an increase in the

complexity of RT1 (Fig. 9.15) general single-channel model

1. with short ISI (< 100 ms), both responses are emitted together (grouping) and both are delayed

2. sometimes RT2 suffers a PRP delay even when the ISI is greater than RT1 feedback The Decision Complexity Advantage

the most restricting limit in human performance relates to the absolute # of decisions/sec rather than the # of bits/sec (cf. bandwidth) – the frequency of decisions and their complexity do not trade off reciprocally decision complexity advantage

some fundamental limit to the central-processing or decision-making rate, independent of decision complexity, that limits the speed of other stages of processing – 2.5 decisions/sec for decisions of the simplest possible kind

Pacing the circumstances under which the operator proceeds from one stimulus to the next


IND641 Engineering Psychology dichotomous dimension

force-paced schedule – constant interval, ISI, independent of the operator’s response self-paced schedule – response-stimulus interval (RSI), depend on the latency of the

operator’s response continuous dimension – defines the value of the timing parameters (RSI, ISI)

Response Factors Response Complexity increased complexity requires more monitoring of the response -- sometimes delay Response Feedback two effects on performance, depending on the sensory modality1. delays, distortions, or elimination of the intrinsic feedback (the perceived sound of one’s voice

or the visualization of one’s moving hand) – substantial deficits in performance2. less serious distortion of extrinsic feedback (the click of a depressed key or the appearance of

a visual letter on a screen – delay or distortion of feedback can be harmful Response Repetition response is slowed by its repetition single trial RT paradigm (repetition is good)

eliminates the repeated engagement of the response selection stage – time saved reaction time relatively long (200 – 300 msec) compared to typing

typing -- response is slowed by its repetition high speed in typing separate responses selected without engaging a higher-level

decision process no longer any benefit to repetitions by bypassing advantageous to employ separate muscle groups for successive responses (advantage for alternation)



Preview and Transcription the class of transcription tasks (e.g., typing, reading aloud, and musical sight reading) allow the

operator to make use of preview, lag, and parallel processing more than one stimulus displayed at a time (preview is available) lag the response behind

perception perception and response are occurring in parallel preview (seeing into the future) or lag (responding behind the present)

possible in self-paced (typing) or force paced (oral translation) tasks maintain a running “buffer” memory of encoded stimuli that have not yet been executed as

responses benefits of lag

1. allowance for variability2. allowance for chunking

Allowance for Variability a steady stream of output at a constant rate can proceed even if input encoding is temporarily

slowed Allowance for Chunking evidence in typing that inputs are encoded in chunks letters in each chunk processed more or

less in parallel the output must be serial encoding, buffer storage, response – proceed in parallel with little mutual interference, and are

even time shared with a fourth mental activity, the monitoring of errors in response



Use of Preview preview helps performance benefits of preview

making available more advance information giving the operator an opportunity to perceive chunks not related to the semantic level of

processing but chunk-sized units to be processed in parallel the benefits of chunking are primarily perceptual and may be seen in storage but not in response

c hapter 9. selection of action

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