Effects of a sub-maximal physical load on the orienting and focusing of visual attention

The effects of a constant, sub-maximal workload (60% VO2max) on visual attention were investigated in two experiments by means of a computerised attentional. test which was performed both at rest and while cycling. Two main aspects of the attentional performance were considered: the orienting of attention in the peripheral visual space (space-based aspect) and the focusing of attention on global and local features of visual objects (object-based aspect). The space-based aspect was investigated by presenting peripheral cues which predicted the size and position of a following target stimulus. The object-based aspect was investigated by means of compound stimuli (e.g. a global "H" letter composed from local "E" letters) containing the target stimulus either at the global or at the local level. Results show the following effects of the sub-maximal workload: (1) a general facilitation of reaction speed; (2) a specific modulation of attention depending on task demands. With higher task demands (i.e. frequent misleading cues), subjects better succeeded in suppressing the automatic orienting triggered by the misleading cue and in directing attention on task relevant global features of visual objects located elsewhere. Thus, the sub-maximal workload might enhance the flexibility in shifting a broad attentional focus in the visual space.