Investigating sequential effects in humans performing a 2AFC psychophysical task

Abstract

Perceptual decision making is the process by which our brain collects and accumulates sensory information and analyzes it to generate an action. However, not only perception is responsible for our decisions but it has been shown that they are also influenced by past choices. Indeed, in a variety of behavioral tasks, the subjects presented sequential effects, i.e. dependencies deriving from previous experiences in the decision-making process. Based on previous studies conducted on rats, we aimed to investigate this matter on human subjects, to analyze similarities and differences between the two species and to verify the extent to which this behavior occurs. To do this, we developed a psychophysical experiment that consists of an auditory task in which the participants have to choose between two alternatives. The experiment was carried out using a software created by the laboratory and run on an iPad, a revolutionary methodology in the field of psychophysics. Analyzing the data obtained we showed that most of the subjects presented sequential effects in the choice between the two alternatives, in particular when the decisions were taken in conditions of perceptual uncertainty.