title: Selective influence of working memory load on exceptionally slow reaction times.
abstract: The rate of exceptionally slow reaction times (RTs), described by the long tail of the RT distribution, was found to be amplified in a variety of special populations with cognitive deficits (e.g., early-stage Alzheimer's disease, attention-deficit/hyperactivity disorder, low intelligence, elderly). Previous individual differences studies found high correlations between working memory (WM) and parameters that characterize the magnitude of the long-RT tail. However, the causal direction remains unknown. In 3 choice-reaction task experiments, we examined this relationship by directly manipulating WM availability. In Experiment 1, the stimulus-response rules were either arbitrary (WM demanding) or nonarbitrary. In Experiment 2, the arbitrary rules were either novel (demanding) or practiced. In Experiment 3, WM was loaded with either declarative (stimulus-stimulus) or procedural (stimulus-response) arbitrary rules. Using an ex-Gaussian model fitting, we found across all experiments that WM demands uniquely influenced the τ parameter, mostly responsible for the long-RT distribution tail. Evidence accumulation modeling of the choice process indicated that WM load had little influence on the decision process itself and primarily affected the duration of an exponentially distributed nondecision component, assumed to reflect the process of rule retrieval. Theoretical interpretations and implications are discussed.
authors.affiliation: Department of Psychology.
authors.forename: Nitzan
authors.initials: N
authors.lastname: Shahar
authors.affiliation: Department of Psychology, Tel-Aviv University.
authors.forename: Andrei R
authors.initials: AR
authors.lastname: Teodorescu
authors.affiliation: Department of Psychology, Tel-Aviv University.
authors.forename: Marius
authors.initials: M
authors.lastname: Usher
authors.affiliation: Department of Psychology.
authors.forename: Maayan
authors.initials: M
authors.lastname: Pereg
authors.affiliation: Department of Psychology.
authors.forename: Nachshon
authors.initials: N
authors.lastname: Meiran
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D002755:Choice Behavior / Q000502:physiology*; D005260:Female; D006801:Humans; D007206:Individuality; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009483:Neuropsychological Tests; D011930:Reaction Time / Q000502:physiology*; D055815:Young Adult