The question whether one’s current emotional state influences one’s cognitive abilities has been investigated in various domains. Positive mood has been shown to modulate cognitive functions, although the exact influence has been shown to vary between different functions: positive affect has been found to either impair or improve performance depending on the specific task. On the one hand, induced positive affect improves verbal fluency (Philips, Bull, Adams, & Fraser, 2002) and reduces interference between competing response alternatives in a Stroop-task (Kuhl & Kazén, 1999). On the other hand, positive affect has been shown to increase response interference due to increased distractibility (Rowe, Hirsh, & Andersen, 2007) and to impair performance on certain executive function tests (Oaksford, Morris, Grainger, & Williams, 1996). A series of studies by Dreisbach and colleagues revealed that positive affect results in flexibility benefits, but also in maintenance costs (distractibility) (Dreisbach, 2006, Dreisbach and Goschke, 2004 and Dreisbach et al., 2005).
The exact effect of positive affect on cognitive control is therefore still unclear. To further delineate the modulatory effects of induced positive affect on cognitive control, we used a task that allowed us to study a specific aspect of cognitive control: the inhibition of reflexive eye movements (‘oculomotor inhibition’). During the so-called antisaccade task, participants either make a saccadic eye movement towards the appearing stimulus after stimulus onset (i.e. prosaccade trials) or a saccade in the opposite direction as quickly as possible (i.e. antisaccade trials). Correct performance in the antisaccade task requires the inhibition of the automatic response to the stimulus onset. Results typically show that antisaccade trials have longer saccade latencies than prosaccade trials and that participants frequently make an erroneous saccade to the stimulus onset in antisaccade trials (Everling and Fischer, 1998 and Hutton and Ettinger, 2006).
Neuropsychological research has revealed that correct performance in the antisaccade task is subserved by brain areas that are also known to be involved in cognitive control. For instance, imaging studies have identified various frontal areas that are active during the antisaccade task such as the frontal eye fields and dorsolateral prefrontal cortex (Everling and Munoz, 2000 and Funahashi et al., 1993). Lesion studies have revealed that successful inhibition in the antisaccade task relies heavily on frontal circuits (Guitton et al., 1985, Pierrot-Deseilligny et al., 1991 and Pierrot-Deseilligny et al., 2003). Furthermore, the amount of erroneous eye movements is known to be increased when a working memory task is performed simultaneously (Mitchell, Macrea, & Gilchrist, 2002) and successful performance in the antisaccade task is linked to working memory capacity (Eenshuistra et al., 2004 and Roberts et al., 1994). Therefore, oculomotor inhibition in the antisaccade task is generally linked to prefrontal cognitive control.
In the current study, it was investigated whether induced positive affect increases the ability to suppress a reflexive saccade in the antisaccade task. Participants performed the antisaccade task twice: once after seeing a neutral movie and once after seeing a movie which is expected to induce positive affect. The amount of erroneous eye movements was compared between the two sessions. In this analysis, a distinction was made between erroneous eye movements with express (80–130 ms) and regular (>130 ms) latencies, because these errors have been argued to reflect different and distinct phenomena (Klein & Fischer, 2005). Whereas express errors seem to reflect reflex-like prosaccades to the stimulus onset, erroneous eye movements with a regular latency reflect errors in the intentional processes associated with the execution of a correct antisaccade (Klein, Rauh, & Biscaldi, 2010). For instance, although erroneous eye movements with a regular latency are correlated with (‘higher’) cognitive measures, like executive function and working memory, similar correlations are absent for express errors (Klein et al., 2010).
If induced positive affect increases cognitive control, as observed in the Stroop-task (Kuhl & Kazén, 1999), this should result in stronger oculomotor inhibition, reflected by a decreased number of erroneous eye movements on antisaccade trials. The analysis of express and regular latencies will provide insight in whether this possible improvement is related to an increased inhibition of reflex-like prosaccades or related to reduced errors in intentional processes, as measured by erroneous eye movement with a regular latency.
