Driving is a complex task that requires a high level of attention for the safe operation of a motor vehicle. However, the human attention system is limited in capacity, and distraction arises when there is a competition for attention from non-driving related activities. When insufficient attention is prioritized to the road ahead, driving safety may be undermined. Cognitive distraction, one form of driver distraction, occurs when attention is withdrawn from the primary task of driving to a competing cognitive event. In this dissertation, I implemented four studies involving behavioural and electrophysiological methods to expand our current understanding of the impact of cognitive distraction on driver attention and performance. The first three studies focused on the emotional side of cognitive distraction, while study four focused on the social and cognitive influence of an in-car passenger. Study one aimed to examine the potential for driver distraction from emotional information presented on roadside billboards. To achieve this, participants operated a driving simulator in the presence of positive, negative, and neutral words. Study two investigated the behavioural and event-related potential (ERP) effects elicited by auditory words of different emotional valence (positive, negative, and neutral) during driving (dual-task) and non-driving (single-task) conditions. The primary goal was to determine whether distraction presented in the auditory modality would produce a similar pattern of effects as visual distraction. The secondary goal was to assess the allocation of neural resources under single and dual-task conditions. Study three aimed to examine the effects of highly arousing taboo-related distraction on driving performance. Participants operated a driving simulator in the presence of non-arousing words, moderately arousing positive and negative words, and highly arousing taboo words, presented on roadside billboards. Study four examined the attentional effects of driving with an in-car passenger, using electrophysiological methods. The objective was to investigate the relationship between attention, cognitive load, and social demands, related to the presence of a passenger. Findings from the first three studies provided novel insights and significant contributions to the literature on driver distraction by: (a) providing evidence that emotion-related distraction can capture and modulate attention to impact driving behaviour, (b) providing evidence that the processing of emotional information while driving likely influences higher-order cognitive processes rather than lower level sensory and perceptual processes, and (c) providing evidence that driving performance is differentially influenced by the valence (positive vs. negative) and arousal (high vs. moderate) of the emotional content; these unique effects reflect separate processes in the attention system, related to how arousal and valence interacts. Study four provided novel insights and significant contributions to the driving literature by: (a) providing evidence that mere presence of a passenger is sufficient to consume driver attentional resources, (b) supporting research in social psychology that describe the social influence of others, and (c) providing evidence that a potential mechanism for the effects of passengers is that they impose additional cognitive demand on the driver's limited resources. Together, these convergent lines of research demonstrate that a main element of cognitive distraction is increased driver workload, which can modulate attention to influence driver attention and performance.