How load bearing can influence cognitive performance : investigated using mobile electroencephalography (EEG) recordings in real-life settings.

Physical load carriage is an essential duty for military personnel. Physical load carriage induces psychological and physiological effects, but the influence of load carriage on brain activity and subsequent cognitive performance is largely unknown. This due to difficulties in disentangling the subtle behavioural effects under load carriage in complex occupational settings. To investigate how load carriage influences cognition directly, continuous measures of brain activity must be obtained in realistic settings. Mobile EEG is ideally suited to this task. Across four studies, mobile EEG recordings were used to assess to what extent load carriage influences attention. Four objectives were defined. 1. To evaluate mobile EEG as a viable tool in real-life settings (studies 1-4). 2. Investigate the influence of walking on attentional processes (study 1, selective attention; study 2, change detection). 3. Establish the impact of load carriage on brain activity during walking (study 3). 4. Assess the interaction of load carriage on attentional processes during walking (study 4). Interpretations of resulting data were conceptualised in the proposed dynamic resource allocation model of cognitive performance. Successful application of Mobile EEG was evident and found signal quality comparable to EEG recorded in a laboratory. Moreover, walking influenced attentional processes in an indirect way, moderated by the environment and concurrent perceptual load. While a steady state neural index of walking was recorded in a natural setting, this was invulnerable to load carriage effects. Further, and most pressing for this thesis, load carriage had little influence on neural indices of attention. Despite this, there is some indication from the data that fatigue plays a prominent role in the interaction of load carriage and cognitive function, and further exploring the neural underpinnings of motivation may prove fruitful in future studies of load carriage and cognitive function