Flexible Processing in Procedural-Based Categorization

1. Results General Methods Introduction References Aims of Study Summary Conclusions Flexible Processing in Procedural-Based Categorization W. Todd Maddox1, J. Vincent Filoteo23 & Grant C. Baldwin1 1University of Texas; 2Veterans Medical Research Foundation, and 3UCSD Perceptual Shift Exp. • Participants: Healthy young adults. • Task: Perceptual categorization task [5]. • Single line stimulus. Length and orientation vary across trials. • Trial procedure: • Session Procedure: • 3 100-trial “pre-change” blocks • 3 100-trial “post-change” blocks • Much evidence supports the existence of neurobiologically distinct category learning systems [e.g., 1 – 4]. • Procedural-based system: mediated by the tail of the caudate nucleus and best suited for (nonverbalizable) information-integration category learning. StimulusResponseFeedback • Pre-change performance equated. "Correct, that was an A" or "Wrong, that was an A" A B • Different stages of procedural-based categorization are differentially impacted by perceptual shifts and stimulus-label switches. • Breaking cortico-caudate connectivity (through perceptual shifts) leads to a large initial performance cost, and slowed re-learning. • Breaking the caudate–pallidal connectivity (through stimulus-label switches) leads to a small initial cost, and slowed relearning. • Breaking the cortico-caudate-pallidal connectivity leads to a large initial performance cost, but fast relearning. Pre-Change Information-Integration Categories • Perceptual shift leads to bigger cost than stimulus-label switch. • Is pre-3 accuracy predictive of cost? • Yes, if a perceptual shift (rPS = .55, rSS = .41) • No, if stimulus-label switch (rSLS = -.14) • (A; see above) Category representation component: Many-to-one mapping from visual areas to the tail of the caudate. • (B; see above) Stimulus-label compatibility component: System associates a response label with a region of perceptual space • Caudate to globus pallidus Post-Change Information-Integration Categories • To determine whether there are different stages of procedural-based category learning. • To determine whether these stages are differentially impacted by: • Stimulus shifts in the perceptual space • Stimulus-label switches • Both • To determine the flexibility of re-learning following these experimental manipulations. • More post changes lead to better re-learning. [1] Ashby, F. G., Alfonso-Reese, L. A., Turken, A. U., & -Waldron, E. M., (1998). A neuropsychological theory of multiple systems in category learning. Psychological Review, 105, 442-481. [2] Ashby, F. G., & Maddox, W. T. (2005). Human Category Learning. Annual Review of Psychology, 56, 149-178. [3] Maddox, W. T., & Ashby, F. G. (2004). Dissociating explicit and procedural-learning based systems of perceptual category learning. Behavioural Processes, 66(3), 309-332. [4] Smith, E.E., Patalano, A.L., & Jonides, J. (1998). Alternative strategies of categorization. Cognition, 65, 167-196. [5] Ashby, F. G., & Gott, R. E. (1988). Decision rules in the perception and categorization of multidimensional stimuli. J Exp Psychol Learn Mem Cogn, 14(1), 33-53. http://homepage.psy.utexas.edu/homepage/group/MaddoxLAB/ • Perceptual shift cost larger than stimulus-label switch cost. • The more “locked in” the larger the cost for perceptual shift, but not stimulus-label switch. • Despite larger initial costs, the more post changes, the better post-change learning.