Perceptual Learning – Perceptual Changes in Learning New Categories : An extended abstract (autoreferat) submitted in partial fulfillment of the requirements for the degree of Ph.D. in Psychology

Abstract

Perceptual learning traditionally focuses on studying early plasticity in the sensory pathways. Categorization is a task typically attributed to relatively higher-level cognition. This dissertation explores whether visual categorization of simple objects involves perceptual learning.
A simple, physiologically plausible neural network model is put forward to demonstrate how both supervised and unsupervised learning could take place in visual categorization. The model shows how early perceptual representations could be formed, adjusted and reorganized without feedback. At the same time, the re-weighting of the connections between low-level representations and mid-level perceptual structures allows the selective filtering of early-level information and the formation through supervised learning of perceptual detectors for characteristic parts of objects. The model demonstrates how perceptual learning processes could take place in seemingly higher-level tasks like categorical learning of simple objects.
Several experiments, using a position transfer paradigm in categorical learning of simple objects, are presented in addition to the new model. They confirm empirically the claims of the model: that visual categorical learning involves lower-level perceptual learning processes. Evidence for such processes is found in the incomplete transfer of learning when the stimuli are presented at a new location in the visual field. This effect is observed even when the participants’ categorization strategy is very simple and explicit. These results complement a large pool of similar findings for arguably lower-level perceptual tasks like vernier discrimination or orientation judgment.
This dissertation argues that visual categorical learning of simple objects involves low-level perceptual learning processes, similar to the processes in typical sensory perceptual tasks.