Nicolaas Prins
Associate Professor of Psychology
Phone Number:
Email: nprins@olemiss.edu
http://psychology.olemiss.edu/nicolaas-prins/

Key Words: Perception

Research Description: The Psychometric Function (PF) relates some behavioral measure (e.g., proportion correct detection) to some task characteristic (e.g., stimulus intensity). Typically of interest is the 'threshold' stimulus intensity. The threshold is usually defined as that stimulus intensity at which observers reach a specific level of performance. Some suggest that, in order to obtain a threshold estimate which is as unbiased as possible, we should allow the upper asymptote of the PF or 'lapse rate' to vary during function fitting. In their influential paper, Wichmann and Hill (2001) claim that allowing the lapse rate to vary results in threshold and slope estimates which are 'essentially unbiased', seemingly irrespective of what stimulus placement regimen is used. In Prins (2012), I have attempted to replicate these results, but was unsuccessful. Instead, I obtained systematic and significant biases in both thresholds and slopes, especially when stimulus placement was controlled by an adaptive method. Prins (2012) discusses the origin of this bias and suggests a few strategies to circumvent this bias. Two of these strategies are currently investigated further in my lab and are mentioned below.

Honors Theses:

Shumake, Maximilian James (2014) An Investigation of the Effects of Hysteresis on the Rotation Percept. (full text)