Event-Related Potentials Elicited by Controlled and Automatic Target Detection
Abstract
When subjects search for the same set of targets over many trials (a training schedule known as consistent mapping or CM), performance can become relatively independent of processing load (defined as the product of the number of targets to be searched for and the number of forms in the display). Search is said to be 'automatic.' In contrast, when the role of distractors and targets is periodically exchanged, search speed is slow and highly dependent on processing load. Search occurring under these varied mapping (VM) conditions is referred to as 'controlled.' The present study attempted to determine whether the high speed search process resulting from CM training occurs without the investment of a limited capacity attention system. The P300 component of the human event related potential (ERP) has been shown to be a sensitive index of the attention required by a variety of tasks. If CM training results in a withdrawal of attention, then CM target detection should be accompanied by smaller P300's than VM detection. Subjects searched for CM and VM targets. ERP's were recorded from frontal (Fz) and parietal (Pz) electrodes both at the beginning and end of a 7 session training period. A large P300 component was observed at Pz in both search tasks with amplitude measurements independent of whether mapping was consistent or varied. In contrast, mapping was related to an 'early' component of the ERP (N1- P2). Under high processing load, a CM target produces additional negativity which may reflect orienting to the target's spatial location.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1981
- Accession Number
- ADA108907
Entities
People
- James E. Hoffman
- Michael R. Houck
- Robert F. Simons
Organizations
- University of Delaware