DOI: 10.1177/20416695231214440 ISSN: 2041-6695

Continuous psychophysics for two-variable experiments; A new “Bayesian participant” approach

Michael Falconbridge, Robert L. Stamps, Mark Edwards, David R. Badcock
  • Artificial Intelligence
  • Sensory Systems
  • Experimental and Cognitive Psychology
  • Ophthalmology

Interest in continuous psychophysical approaches as a means of collecting data quickly under natural conditions is growing. Such approaches require stimuli to be changed randomly on a continuous basis so that participants can not guess future stimulus states. Participants are generally tasked with responding continuously using a continuum of response options. These features introduce variability in the data that is not present in traditional trial-based experiments. Given the unique weaknesses and strengths of continuous psychophysical approaches, we propose that they are well suited to quickly mapping out relationships between above-threshold stimulus variables such as the perceived direction of a moving target as a function of the direction of the background against which the target is moving. We show that modelling the participant in such a two-variable experiment using a novel “Bayesian Participant” model facilitates the conversion of the noisy continuous data into a less-noisy form that resembles data from an equivalent trial-based experiment. We also show that adaptation can result from longer-than-usual stimulus exposure times during continuous experiments, even to features that the participant is not aware of. Methods for mitigating the effects of adaptation are discussed.

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