The relative importance of perceptual and memory sampling processes in determining the time course of absolute identification.

Abstract

Perceptual and memory sampling in absolute identification 2 2 Abstract In absolute identification, the EGCM-RT (Kent & Lamberts, 2005, 2016 proposes that perceptual processing determines systematic response time (RT) variability; all other models of RT emphasise response selection processes. In the EGCM-RT the bow effect in RTs (longer responses for stimuli in the middle of the range) occurs because these middle stimuli are less isolated and so as perceptual information is accumulated, the evidence supporting a correct response grows more slowly than for stimuli at the ends of the range. More perceptual information is therefore accumulated in order to increase certainty in response for middle stimuli, lengthening RT.According to the model reducing perceptual sampling time should reduce the size of the bow effect in RT. We tested this hypothesis in two pitch identification experiments. Experiment 1 found no effect of stimulus duration on the size of the RT bow. Experiment 2 used multiple short stimulus durations as well as manipulating set size and stimulus spacing. Contrary to EGCM-RT predictions, the bow effect on RTs was large for even very short durations. A new version of the EGCM-RT could only capture this, alongside the effect of stimulus duration on accuracy, by including both a perceptual and a memory sampling process. A modified version of the SAMBA model (Brown, Marley, Donkin, & Heathcote, 2008) could also capture the data, by assuming psychophysical noise diminishes with increased exposure duration. This modelling suggests systematic variability in RT in absolute identification is largely determined by memory sampling and response selection processes.Keywords. Absolute identification, perceptual processing, memory sampling, response selection Perceptual and memory sampling in absolute identification 3 3The relative importance of perceptual and memory sampling processes in determining the time course of absolute identificationThe last 30 years has seen the development of several detailed mathematical models of the time course of cognitive processes. These models specify how, over the time course of a cognitive process, information about a stimulus is sampled and integrated into a decision mechanism. Such models have been applied successfully to a wide range of cognitive tasks and have been influential in helping understand the processes underlying such tasks (e.g., Smith & Ratcliff, 2009). An important distinction between these models is the emphasis placed on what is being sampled. In some models, there is a great emphasis on the importance of perceptual processing (Adelman, 2011; Guest & Lamberts, 2010, 2011Lamberts, 2000, Kent & Lamberts, 2005, 2006a, 2016. These models suggest that, over the time course of a trial, a representation of a stimulus is gradually built up through repeated sampling of the stimulus such that the information that is fed into the decision process changes over time. In such models (e.g., Lamberts, 2000) task performance at a given point in time is limited by the state of ...

Stimulus probability effects in absolute identification.

“…However, currently the memory aspect of the EGCM-RT is underdeveloped and additional work is required to develop a more complete memory process of the EGCM-RT. For example, including a mechanism through which the rate at which information is accumulated from memory is partly determined by the strength of the memory representation, which depends upon its overall dissimilarity to other exemplars, can produce a bow in d ′ i,i + 1 (see Guest, Kent, & Adelman, 2015).…”

“…In addition, the memory mechanism in the EGCM-RT responsible for generating the bias for high-frequency stimuli is underspecified. We have recently developed a more detailed memory mechanism for the EGCM-RT, which entailed memory sampling in an analogous manner to perpetual sampling (Guest et al, 2015). However, the purpose of this study was not to rigorously test model implementations but to show the importance of long-term representations more generally to performance in absolute identification.…”

A unified theory of discrete and continuous responding.

“…These "set-size" effects are typically thought to reflect a limit on performance in terms of the amount of information transmitted (Miller, 1956). The lengthening response times and shrinking accuracy toward the center of the scale have previously been attributed to perceptual and memory processes (Guest et al, 2018) or to perceptual processes alone (Lamberts, 2000)-we test these proposals by leaving the stimulus on-screen in our experiments, to focus on perceptual and response processes. Although in typical absolute identification paradigms the number of stimuli and responses are the same, Lacouture et al (1998) found that almost all of the set-size effect, and much of the bow effect, are due to the number of responses rather than number of stimuli when the two factors are manipulated separately.…”

A unified theory of discrete and continuous responding

“…These "set-size" effects are typically thought to reflect a limit on performance in terms of the amount of information transmitted (Miller, 1956). The lengthening response times and shrinking accuracy toward the center of the scale can be attributed to both memory sampling and response processes (Guest et al, 2018) -we leave the stimulus on-screen in our experiments to focus on the latter process. Although in typical absolute identification paradigms the number of stimuli and responses are the same Lacouture et al (1998) found that almost all of the set-size effect, and much of the bow effect, are due to number of responses rather than number of stimuli when the two factors are manipulated separately.…”