Multiple stages of learning in perceptual categorization: evidence and neurocomputational theory.
Virtually all current theories of category learning assume that humans learn new categories by gradually forming associations directly between stimuli and responses. In information-integration category-learning tasks, this purported process is thought to depend on procedural learning implemented via dopamine-dependent cortical-striatal synaptic plasticity. This article proposes a new, neurobiologically detailed model of procedural category learning that, unlike previous models, does not assume associations are made directly from stimulus to response. Rather, the traditional stimulus-response (S-R) models are replaced with a two-stage learning process. Multiple streams of evidence (behavioral, as well as anatomical and fMRI) are used as inspiration for the new model, which synthesizes evidence of multiple distinct cortical-striatal loops into a neurocomputational theory. An experiment is reported to test a priori predictions of the new model that: (1) recovery from a full reversal should be easier than learning new categories equated for difficulty, and (2) reversal learning in procedural tasks is mediated within the striatum via dopamine-dependent synaptic plasticity. The results confirm the predictions of the new two-stage model and are incompatible with existing S-R models.
University of California, Santa Barbara, CA, USA.
George
G
Cantwell
University of California, Berkeley, CA, USA.
Matthew J
MJ
Crossley
Department of Psychological & Brain Sciences, University of California, Santa Barbara, CA, 93106, USA. ashby@psych.ucsb.edu.
F Gregory
FG
Ashby
D006801:Humans; D008960:Models, Psychological; D009473:Neuronal Plasticity; D011582:Psychological Theory; D012193:Reversal Learning
Categorization; Procedural learning; Striatum