Evoked Response Measures of Resource Allocation: Effects of Primary Task Load. II

摘要

The work-load paradigm (Ogden, et al., 1979) has been used extensively in research concerning the psychological aspects of evoked potentials (Donchin, 1976, 1977). Typically a perceptual motor task is used as the primary task while an uncertainty task such as the odd-ball (Sutton, 1965) paradigm is used as a secondary task. The subject is required to perform the primary task at predetermined levels of difficulty while attending to rare occurring auditory stimuli. The evoked potential is measured in response to the target stimuli and an effort is made to infer, from components of the event related potential (ERP), psychological parameters such as attention and arousal. A determination is made as the distribution of resources assigned to the tasks. Isreal et al (1978) indicated that increasing the primary task load resulted in a precipitous drop in the P3 component of ERP. Results of our study (Elfner, 1978) showed no degradation in the P3 wave as a function of task difficulty on the primary task. The task in the latter study was to track a forced-function moving target on a cathode ray tube display. Subjects were instructed in the task to achieve stable performance levels at the difficulty levels employed; the major difference in the secondary task was that a random inter-stimulus interval (ISI) was employed. Donchin typically employs a fixed ISI. It would appear from the results of Elfner (1978) that the presence of random ISI in the secondary task considerably increases the resource allocation applied to the secondary task as evidenced by the large P3 component of ERP.