The Microstructure of Dual Task Interaction. 2. The Effect of Task Instructions on Attentional Allocation and a Model of Attention-Switching

As an extension of an experimental design reported previously the microstructure of dual task interaction was investigated in a condition in which task instructions favoured the task which had previously been designated the secondary task.

In the situation explored in this paper subjects worked on the five-choice serial reaction task (designated secondary task) whilst at the same time they received single auditory digits at random time intervals, performed a transform operation (adding seven), and called the answer out into a voice key.

The nature of the interaction was investigated using fine analysis of data, and it is argued that the results give further support to the view that subjects were processing information sequentially. A change in the patterning of serial responses in the interval defined by the digit stimulus (D_s) and the digit response (D_r) under the changed-instructions condition suggested that individuals are able to play an active role in the ordering of the attention process in sequential processing situations. ‘Process theory’, in which the information processing state of the main task is considered to have a direct influence on the response to the secondary task signal, is argued to be of little use in explaining the data. Two types of explanations based on criterion theory are considered—one which involves criterion setting with respect to a direct time base and one which relies on information processing stage, as an indirect time base.

It is argued that the microstructure of dual task interaction should be investigated more closely and that the ordering of the time-sharing process is a skill.