Category learning can alter perception and its neural correlates

• Published in: PloS one Vol. 14; no. 12; p. e0226000
• Main Authors: Pérez-Gay Juárez, Fernanda, Sicotte, Tomy, Thériault, Christian, Harnad, Stevan
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 06.12.2019; Public Library of Science (PLoS)
• Subjects: Adolescent; Adult; Amplitudes; Auditory evoked potentials; Biology and Life Sciences; Brain; Brain - physiology; Brain Mapping; Categories; Color; Comparative analysis; Compression; Compression tests; Dictionaries; Electroencephalography; Error correction; Event-related potentials; Evoked Potentials; Feedback; Female; Humans; Hypotheses; Judgments; Learning; Learning - physiology; Male; Medicine and Health Sciences; Names; Neurophysiology; Perception; Perceptions; Photic Stimulation; Physiological aspects; Physiology; Research and Analysis Methods; Sensors; Separation; Social Sciences; Visual discrimination learning; Visual Perception; Young Adult; Canada
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0226000

Learned Categorical Perception (CP) occurs when the members of different categories come to look more dissimilar ("between-category separation") and/or members of the same category come to look more similar ("within-category compression") after a new category has been learned. To measure learned CP and its physiological correlates we compared dissimilarity judgments and Event Related Potentials (ERPs) before and after learning to sort multi-featured visual textures into two categories by trial and error with corrective feedback. With the same number of training trials and feedback, about half the subjects succeeded in learning the categories ("Learners": criterion 80% accuracy) and the rest did not ("Non-Learners"). At both lower and higher levels of difficulty, successful Learners showed significant between-category separation-and, to a lesser extent, within-category compression-in pairwise dissimilarity judgments after learning, compared to before; their late parietal ERP positivity (LPC, usually interpreted as decisional) also increased and their occipital N1 amplitude (usually interpreted as perceptual) decreased. LPC amplitude increased with response accuracy and N1 amplitude decreased with between-category separation for the Learners. Non-Learners showed no significant changes in dissimilarity judgments, LPC or N1, within or between categories. This is behavioral and physiological evidence that category learning can alter perception. We sketch a neural net model predictive of this effect.