| Abstract: | Processing in various skilled domains is often described as automatic, in the sense that functional stimulus processing is triggered by stimulus onset and cannot be interrupted. One problem is that subjects typically know what task they have to perform prior to stimulus presentation. Various effects attributed to automatic processing may, therefore, arise instead from the mental set that is already in place. In the present study, we investigated skilled subjects’ ability to engage in processing prior to knowing what the task is. A numeral was presented, and subjects either named it or added 1 and named the result. Which task was to be performed on a trial was signaled by a tone that appeared before or at the same time as the target. If functional target processing is triggered by its presentation, the effect of low contrast should be absorbed into the time taken to decode the task cue, regardless of the task (the effect of contrast should be absent at the 0-msec stimulus onset asynchrony [SOA] and present when task information is given in advance of the target). An underadditive interaction between contrast and SOA was seen for one task, but these factors had additive effects in the other task. This pattern can be understood in terms of the hypothesis that although encoding can be thought of as a stage common to both tasks, it is not, in the present context, functionally independent of a subsequent stage unique to a task. |
