Authors:

MANLY, T., Davison, B., Heutink, J., Galloway, M. & Robertson, I.H.

Reference:

Year of publication:

2000

CBU number:

4107

Abstract:

Traumatic brain injuries are associated with an increased frequency of 'absentminded' slips of action. As such errors tend to occur in routine situations, assessment in the clinic or laboratory has proved difficult. Recently, however, Robertson and colleagues described a simple and reliable computerised measure, the Sustained Attention to Response Test (SART) that was predictive of such error propensity in both head injured and control groups. In the SART, participants are asked to respond to frequent 'go' stimuli but maintain a readiness to withhold a response to rare and unpredictable no-go trials. Here, data from 109 healthy participants is pooled to allow more detailed analysis of the relationships between speed of 'go' responses and accuracy on 'no-go' trials. The results show that individual differences in response speed are related to error rates, but that variability within individuals' reaction times (RT) is also a strong predictor. To clarify whether such variability is itself occasioned by lapsing attention, a 'response locked' version of the SART task was developed to reduce both individual differences and within-subject variability in RT. While both aims were successful, no significant change in error rates was observed and the performance on the modified task was strongly related to standard SART performance. The results suggest that a significant component in RT variability is related to the same pattern of lapsing attention that underpins errors and that reducing these differences 'at source' may do little do undermine the sensitivity of the task.