title: The location and interpretation of the bisection point.
abstract: In a temporal bisection task with humans, the observer is required to decide whether a probe duration (t) is more similar to the short referent (S), an R(S) response, or to the long referent (L), an RL response. Temporal bisection yields a psychometric function relating the proportion of long responses, P(R(L)), to probe duration t. The value of t at which R(S) and R(L) occur with equal frequency, P(R(L)) = .5, is referred to as the bisection point, T1/2. Bisection models usually interpret T1/2 as identifying the value of t that is equally confusable with S and L, but they differ in their predictions for the location of T1/2. The present paper presents new data relevant to the location and interpretation of T1/2. The data indicate that the empirical values usually are biased, the biases being influenced by duration range, L:S ratio, and probe spacing. Moreover, the biases often are not consistent across observers. It is concluded that empirical values of T1/2 should not be interpreted as indicating the value of t that is equally confusable with S and L.
authors.affiliation: Department of Psychology, McMaster University, Hamilton ON, Canada. allan@mcmaster.ca
authors.forename: Lorraine G
authors.initials: LG
authors.lastname: Allan
mesh_terms: D000465:Algorithms; D001288:Attention / Q000502:physiology; D004193:Discrimination Learning; D006801:Humans; D008960:Models, Psychological; D015588:Observer Variation; D011601:Psychophysics; D013998:Time Perception