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Kornblum, S. (1992). Dimensional overlap and dimensional relevance in stimulus-response and stimulus-stimulus compatibility.

NOTE: This page is a short summary of the paper. The full text of the manuscript is not currently available online.

This paper begins by recapitulating some of the properties and processing principles of the DO model that were presented in the 1990 paper (Kornblum et al.1990), and then expands the number of ensemble in the taxonomy from 4 to 8.  It also includes data showing the effects of the number of alternatives in Type 1 and Type 2 ensembles.

Donders was the first to show that RT increases as a function of the number of alternatives (n); that increase is linear when calculated as a function of log n.  The data from ten different studies in the literature that used ensembles Types 1 and 2, show that: 1. the slope of that function (RT = log n) changes with different ensembles, and mappings – it is steepest when the mapping is random (i.e. no DO, Type 1), shallowest when the mapping is congruent (S-R DO, Type 2), and in between when the correct response could be identified by rule (DO Type 2).  These results are consistent with our model where, depending on the mapping instructions, the response identification process proceeds in one of three ways: 1. the identity rule, 2. a rule other than the identity rule, but a rule nevertheless (which depends on there being DO), and 3.searching through a list.  Fitts explained the S-R compatibility effects as the result of information being processed at different levels of efficiency, which is exactly what the automatic, and different identification processes in our model does.

Preliminary results from one of the experiment in Kornblum & Lee (1995) are also presented: with S-R DO (Type 2), there is a 203 ms mapping effect for the relevant stimulus, and a ~50 ms mapping effect for the irrelevant stimulus.  When there is no S-R DO (Type 1), there is no effect of mapping at all.

 
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Oliver, L., & Kornblum, S. (1991). Dimensional overlap and population stereotype as joint predictors of stimulus-response compatibility.

NOTE: This page is a short summary of the paper. The full text of the manuscript is not currently available online.

Fitts argued that if two S-R ensembles have the same value on the  “population stereotype” scale, they would generate the same size S-R compatibility effects (i.e. RT difference between congruent and incongruent mapping).  According to the DO model, this need not be the case: two ensembles could have the same value of population stereotype, but differ in their degree of dimensional overlap.  In that case, because the compatibility effect is jointly determined at the set and at the element levels, the ensemble with the higher degree of dimensional overlap would generate the larger compatibility effect.  This is the proposition that was tested in this study.

Three stimulus and three response sets were combined to forms nine S-R ensembles.  The population stereotype and the level of dimensional overlap were obtained for each ensemble.  The population stereotype was obtained by asking subjects to give what they thought would be the best mapping between elements of the stimulus set onto elements of the response set. The dimensional overlap was obtained by asking subjects to compare pairs of S-R ensembles, and chose that pair that had the better matching stimulus and response sets. Dimensional overlap was quite strong for some ensembles, and population stereotype was strong in others, thus providing the precise conditions needed to test our proposition.

These nine ensembles were used to construct choice RT tasks with two mapping instructions.  One mapping was congruent, and corresponded to the population stereotype; the other was incongruent (and there were three different incongruent mappings).

The fastest mean RT was obtained for the congruent mapping, and as the degree of dimensional overlap decreased, the mean congruent RT increased.  The RT for incongruent mapping was, of course, longer and it increased with increasing degrees of dimensional overlap.  Both, the decrease in the case of the congruent mapping, and the increase in the case of the incongruent mapping, are in accord with the model.

Assuming that our measures of the level of the population stereotype, and the degree of dimensional overlap are valid, the results of this study confirm our proposition.

 
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Kornblum, S., & Zhang, H. (1991). The Time Course of Automatic Response Activation Process in Stimulus-Response Compatibility.

NOTE: This page is a short summary of the paper. The full text of the manuscript is not currently available online.

Using a four-choice task, this study was designed to test whether: 1. the order of RT that is predicted by the model could be confirmed, i.e. RT was fastest for congruent mappings, slowest for incongruent mappings, and in between for neutral; and 2. in the case of ensembles with S-R overlap, can the automatic activation of the corresponding response element by the presentation of a stimulus element, as is postulated by the model, be demonstrated.

Result 1.  The results confirmed the order of RT’s as predicted by the model.

Result 2.  By reducing the time available to process and execute the response, thus increasing the likelihood of errors, the results showed that when the mapping was incongruent most of the erroneous responses were response that would have been correct had the mapping been congruent, thus demonstrating the activation of the response that would have been correct, had the mapping been different.  However, by reducing the time available to abort, reprogram, etc. which is called for when the mapping is incongruent (ergo generating errors), automatic activation of the response was verified.  Thus, this study confirmed one prediction, and verified an important assumption of the model.

 
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Kornblum, S., Hasbroucq, T., & Osman, A. (1990). Dimensional Overlap: Cognitive Basis for Stimulus-Response Compatibility – A model and taxonomy

1990 is the year the dimensional overlap model (DO) first saw the light of day.  Paul Fitts (Fitts and Seeger, 1953; Fitts & Deininger, 1954) had identified a family of tasks in which performance could not be accounted for by either the stimulus properties alone, nor the response properties alone – the results were clearly the outcome of an interaction between the two.  He called the phenomenon “stimulus response compatibility effect”.

We proposed that this interaction occurred at two levels: the first, where categorical stimulus and response sets are perceived as corresponding or not.  We called the basis of this correspondence the dimensional overlap between the sets.  Dimensional overlap was defined as the degree to which attributes in the two sets are perceptually, structurally or conceptually similar.  It is, therefore, a property of the mental representation of sets.  When dimensions in a stimulus and response set overlap, a second level comes into play: the instructions that map individual stimulus elements onto individual response elements.

This early form of the model already included a taxonomy with four ensembles – which was later expanded to the final eight-task taxonomy in Kornblum (1992), It had a rudimentary architecture, and the outlines of a processing model that combines automatic and control mechanisms.

 
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