It is interesting that there is a finding in cognitive research on absolute identification (AI) that participants can normally discriminate between stimuli that are different (such as red and black size 8 shoes), but there is a greater error when trying to differentiate between the same stimuli. With regard to repeatedly choosing sizes 7 and 9 when looking for an 8, even though 8 is a very popular size in women’s shoes, it may be because there is only minimal difference between a 7 to an 8, or an 8 to a 9. Arrangement of the shoes in numerical size order would increase the likelihood of such a mistake because the differences between the sizes of the same type of shoe would be minimal and not stand out. Absolute identification processes mean that a person learns unique associations between stimuli that are variable on a simple perceptual level, such as color, texture, smell, taste, or shape. Central stimuli, in this case, size 8, and its neighbors sizes 7 and 9, and stimuli in large sets (such as a style lined up from smallest to largest size) have been found to be responded to more slowly and significantly less accurate. In contrast, when stimuli are widely spaced, there is a tendency for a person to respond slightly more accurately (as when shoes are displayed not in rows but on different display heights and distances from each other), although widely spaced stimuli tend to also be responded to slightly more slowly, as compared to stimuli that are narrowly spaced. Evidently, there is a cognitive capacity trade-off between accuracy and speed. In a shoe store, it is likely that the accuracy of obtaining the desired size would be a more important factor. Even though the modern-day maxim tends to be “faster faster” and “I want it now,” if accuracy is low, then the customer will have to wait longer, so accuracy again may tend to be the favored factor when a salesperson is choosing a size wanted by the customer.
This limit in the absolute identification of stimuli is supported across a range of sensory stimuli (not just shoes), and it has been concluded this indicates a fundamental property of human cognition.
Again the more similar the stimuli, the more likely it is to appear as simple stimuli, and the central limit will apply. So that shoes that are most different in styles should be responded to quicker and more accurately, and the closer the styles are in similarity, the longer a salesperson’s responsibility to identify them should be, and also less accurate. Also, there are sequential effects at play, meaning that assimilation to recent responses (i.e., the last style identified) and contrast to less recent responses (i.e., the first style identified) will result in slower and less accurate identification in the former, and vice versa in the latter. It appears that the reduction of similarity when mixing styles together enhances the speed and accuracy of absolute identification. Further, individuals tend to have a higher accuracy of absolute identification when there is only a limited number (<7) of distinct unidimensional stimuli (such as shoe styles). It appears to be that as n approaches 7 a person will increase the number of errors they make with absolute identification, as well as responding more slowly. Whereas with comparative judgments, there is much greater differentiation between pairs of a and b. However, across more complex stimuli, absolute identification accuracy has been noted to increase. This finding complements literature about capacity limits when identifying simple (unidimensional) stimuli, although not complex stimuli. There seems to be an opposite type of processing deficit between the identification of simple and complex stimuli so that a person is normally able to process a highly variable set of stimuli more efficiently as a function of the choices available.
It would be possible to train a salesperson to increase accuracy and speed of absolute identification higher than 7 by reorganizing displays and storerooms to take advantage of differences between styles, placing those most similar at greater distances from each other. However, there is a cognitive capacity limit, and it is likely to be rare that a salesperson could achieve a consistently higher than average accuracy and speed rate above 10 styles.