3.1. Hits and Reaction Times

In the overt blocks, one two-tailed t-test compared participants’ RTs between the first, the second, and the third part of each (baseline and bias) session for non-preferred and preferred intentions. This analysis was conducted to assess the influence of the bias over time.

In the covert blocks, a 2x2x3 repeated-measures ANOVA was performed between groups for each (baseline and bias) session on both RTs and hits. Analyses were made with group (comparison vs. schizophrenic patients) as a between-subjects factor, Bias (preferred vs. non-preferred intention) and Amount of Visual Information (low, moderate and high) as within-subjects factors. Post-hoc Fisher tests were then performed to identify differences between conditions. These same analyses were conducted for each of the 4 experiments. Finally, whenever the variance structure did not conform to the requirements for parametric analyses, logarithmic transformations were used to obtain the required conformity.

For all the analyses, a p<.05 was taken as the criterion for significance. These analyses were performed using the statistical software Statistica 7 ( www.statsoft.com ).