title: Attention, predictive learning, and the inverse base-rate effect: evidence from event-related potentials.
abstract: We report the first electrophysiological investigation of the inverse base-rate effect (IBRE), a robust non-rational bias in predictive learning. In the IBRE, participants learn that one pair of symptoms (AB) predicts a frequently occurring disease, whilst an overlapping pair of symptoms (AC) predicts a rarely occurring disease. Participants subsequently infer that BC predicts the rare disease, a non-rational decision made in opposition to the underlying base rates of the two diseases. Error-driven attention theories of learning state that the IBRE occurs because C attracts more attention than B. On the basis of this account we predicted and observed the occurrence of brain potentials associated with visual attention: a posterior Selection Negativity, and a concurrent anterior Selection Positivity, for C vs. B in a post-training test phase. Error-driven attention theories further predict no Selection Negativity, Selection Positivity or IBRE, for control symptoms matched on frequency to B and C, but for which there was no shared symptom (A) during training. These predictions were also confirmed, and this confirmation discounts alternative explanations of the IBRE based on the relative novelty of B and C. Further, we observed higher response accuracy for B alone than for C alone; this dissociation of response accuracy (B>C) from attentional allocation (C>B) discounts the possibility that the observed attentional difference was caused by the difference in response accuracy.
authors.affiliation: School of Psychology, Plymouth University, Drake Circus, Plymouth PL4 8AA, UK. Electronic address: andy.wills@plymouth.ac.uk.
authors.forename: Andy J
authors.initials: AJ
authors.lastname: Wills
authors.affiliation: School of Psychology, Exeter University, Exeter EX4 4QG, UK. Electronic address: a.lavric@exeter.ac.uk.
authors.forename: Aureliu
authors.initials: A
authors.lastname: Lavric
authors.affiliation: School of Psychology, Exeter University, Exeter EX4 4QG, UK. Electronic address: yvonne.hemmings@btinternet.com.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Hemmings
authors.affiliation: School of Psychology, Exeter University, Exeter EX4 4QG, UK. Electronic address: edward.surrey@gmail.com.
authors.forename: Ed
authors.initials: E
authors.lastname: Surrey
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology*; D008297:Male; D055815:Young Adult
keywords: Categorization; EEG; Learning; Visual attention