title: Fitting an ex-Gaussian function to examine costs in event-based prospective memory: evidence for a continuous monitoring profile.
abstract: Event-based prospective memory (PM) tasks require individuals to remember to perform a deferred action when a target event occurs. PM task requirements can slow ongoing task responses on non-target trials ('costs') under conditions where the defining features of targets are non-focal to the ongoing task, which is indicative that individuals have allocated some form of cognitive control process to the PM task. Recent fits of the ex-Gaussian mathematical function to non-target trial response distributions by prior studies have indicated that these control processes are transiently allocated. In the current paper, fits of the ex-Gaussian function to data reported by Loft and Humphreys (2012) demonstrate a shift in the entire response time distribution (μ) and an increase in skew (τ) for a non-focal PM condition required to remember to make a PM response if presented with category exemplars, compared to a control condition. This change in μ is indicative of a more continuous PM monitoring profile than that reported by prior studies. In addition, within-subject variability in μ was reliably correlated with PM accuracy, suggesting that these control processes allocated on a regular basis were functional to PM accuracy. In contrast, when the ongoing task directed attention to the defining features of targets (focal PM) there was a trend level increase in μ, but the within-subject variability in μ was not correlated with PM accuracy, consistent with the theoretical premise that focal PM tasks are not as dependent on cognitive control as non-focal PM tasks.
authors.affiliation: The University of Western Australia, Australia. Electronic address: shayne.loft@uwa.edu.au.
authors.forename: Shayne
authors.initials: S
authors.lastname: Loft
authors.affiliation: The University of Western Australia, Australia.
authors.forename: Vanessa K
authors.initials: VK
authors.lastname: Bowden
authors.affiliation: Arizona State University, United States.
authors.forename: B Hunter
authors.initials: BH
authors.lastname: Ball
authors.affiliation: Arizona State University, United States.
authors.forename: Gene A
authors.initials: GA
authors.lastname: Brewer
mesh_terms: D001288:Attention / Q000502:physiology*; D003657:Decision Making / Q000502:physiology*; D005260:Female; D006801:Humans; D007600:Judgment / Q000502:physiology*; D008297:Male; D061212:Memory, Episodic; D016011:Normal Distribution; D011930:Reaction Time / Q000502:physiology*; D055815:Young Adult
keywords: Ex-Gaussian function; Learning & Memory; Prospective memory; Response costs; Target focality