3.2. Bias effect

To assess the influence of the participants’ prior expectations on their performance, and to determine whether this influence varied depending on the type of the intention considered, a ‘bias effect’ score for both groups was computed across all experiments. This score was obtained by subtracting, in the bias session, the rate of correct responses for the preferred intention to that one of non-preferred intentions. Thus, the greater this score, the more participants responded toward the preferred (i.e. biased) intention; that is, the greater they relied on their priors to make their decision.

This score was then input as a dependent variable in a 3x2x4 repeated-measures ANOVA with Amount of Visual Information (low, moderate and high) as a within-subjects factor, and group (comparison vs. schizophrenic patients) and Type of Intention (motor vs. superordinate vs. social motor vs. social superord.) as between-subjects factors.