Dissociable perceptual-learning mechanisms revealed by diffusion-model analysis

Abstract

Performance on perceptual tasks improves with practice. Most theories address only accuracy data and tacitly assume that perceptual learning is a monolithic phenomenon. The present study pioneers the use of response time distributions in perceptual learning research. The 27 observers practiced a visual motion-direction discrimination task with filtered-noise textures for four sessions with feedback. Session 5 tested whether the learning effects transferred to the orthogonal direction. The diffusion model (Ratcliff, Psychological Review, 85, 59-108, 1978) achieved good fits to the individual response time distributions from each session and identified two distinct learning mechanisms with markedly different specificities. A stimulus-specific increase in the drift-rate parameter indicated improved sensory input to the decision process, and a stimulus-general decrease in nondecision time variability suggested improved timing of the decision process onset relative to stimulus onset (which was preceded by a beep). A traditional d' analysis would miss the latter effect, but the diffusion-model analysis identified it in the response time data.

Retest reliability of the parameters of the Ratcliff diffusion model

“…As a comparison of the first with the second session revealed, parameters changed over time (e.g., drift rate increased from the first to the second session). Our results are in line with findings from Dutilh et al (2009) who also observed practice effects (see also Petrov, Van Horn, & Ratcliff, 2011). In addition to these general changes, interindividual differences in changes over sessions are plausible and they can contribute to lower retest coefficients.…”

Modeling individual differences in response time and accuracy in numeracy

“…This reduction is similar to what has been obtained in other studies that have manipulated speed/accuracy instructions (Ratcliff et al, 2001; 2003; 2004). There was also a reduction in nondecision times, which might be due to a reduction in times for encoding and response execution, practice effects (because Experiments 7 and 8 always took place in the second session), or both (e.g., Ratcliff et al, 2006b; Petrov, Van Horn, & Ratcliff, 2011; see also Rinkenauer et al, 2004). …”

Testing theories of post-error slowing

“…In these tasks and others, the model has been used to decompose the behavioral effects of phenomena such as practice (Dutilh et al, 2009; Dutilh, Krypotos, & Wagenmakers, 2011; Petrov, Horn, & Ratcliff, 2011), aging (Ratcliff, Thapar, & McKoon, 2001, 2006, 2010), psychological disorders (White, Ratcliff, Vasey, & McKoon, 2009, 2010a, 2010b), sleep deprivation (Ratcliff & Van Dongen, 2009), intelligence (Ratcliff, Schmiedek, & McKoon, 2008; Schmiedek, Oberauer, Wilhelm, Süß, & Wittmann, 2007; van Ravenzwaaij, Brown, & Wagenmakers, 2011), and so forth.…”