Arousal facilitates involuntary eye movements.

Attention plays a critical role in action selection. However, the role of attention in eye movements is complicated as these movements can be either voluntary or involuntary, with, in some circumstances (antisaccades), these two actions competing with each other for execution. But attending to the location of an impending eye movement is only one facet of attention that may play a role in eye movement selection. In two experiments, we investigated the effect of arousal on voluntary eye movements (antisaccades) and involuntary eye movements (prosaccadic errors) in an antisaccade task. Arousal, as caused by brief loud sounds and indexed by changes in pupil diameter, had a facilitation effect on involuntary eye movements. Involuntary eye movements were both significantly more likely to be executed and significantly faster under arousal conditions (Experiments 1 and 2), and the influence of arousal had a specific time course (Experiment 2). Arousal, one form of attention, can produce significant costs for human movement selection as potent but unplanned actions are benefited more than planned ones.

Reward, context, and human behaviour.

Animal models of reward processing have revealed an extensive network of brain areas that process different aspects of reward, from expectation and prediction to calculation of relative value. These results have been confirmed and extended in human neuroimaging to encompass secondary rewards more unique to humans, such as money. The majority of the extant literature covers the brain areas associated with rewards whilst neglecting analysis of the actual behaviours that these rewards generate. This review strives to redress this imbalance by illustrating the importance of looking at the behavioural outcome of rewards and the context in which they are produced. Following a brief review of the literature of reward-related activity in the brain, we examine the effect of reward context on actions. These studies reveal how the presence of reward vs. reward and punishment, or being conscious vs. unconscious of reward-related actions, differentially influence behaviour. The latter finding is of particular importance given the extent to which animal models are used in understanding the reward systems of the human mind. It is clear that further studies are needed to learn about the human reaction to reward in its entirety, including any distinctions between conscious and unconscious behaviours. We propose that studies of reward entail a measure of the animal's (human or nonhuman) knowledge of the reward and knowledge of its own behavioural outcome to achieve that reward.

Differential effects of reward and punishment on conscious and unconscious eye movements.

Very little is known about how human movements are influenced by abstract rewards and punishments relevant for human behaviour. The purpose of this study was to expand our knowledge of the behavioural effects of monetary reward and punishment. We introduced a high and low reward and punishment scheme into an antisaccade task where trials were either rewarded for a correct response (+1 or +25p) or punished for an incorrect response (-1 or -25p). The monetary value of the trial was indicated by the go signal, so subjects had to both program the location of the movement and determine the valence in the short interval before the eye movement was executed. We analysed both correct antisaccade responses and prosaccade errors. Importantly, the errors in this task can be either conscious (recognised) or unconscious (unrecognised). Saccades in both high-reward and high-punishment trials were slowed compared to saccades in low-reward and low-punishment trials, respectively. Therefore, unlike moderate rewards only (Blaukopf and DiGirolamo in Exp Brain Res 167:654-659, 2005), combining rewards and punishments and increasing motivation levels leads to a delay in movement execution during high valence trials where all actions are slowed, even errors. However, unconscious errors were differentially affected as they were speeded when punishment was high. We conclude that reward and punishment similarly influence the programming of conscious movements, but the strong saliency for punishment affords unconscious errors immunity from this delay.

The automatic extraction and use of information from cues and go signals in an anti-saccade task.

In a gap antisaccade task that exogenously cues the side that subjects should antisaccade to, subjects find it hard to look away from the suddenly appearing go signal. Surprisingly, subjects are unaware of the majority of the prosaccade errors they make, and these errors remain unrecognised even when corrected by a second saccade requiring twice the amplitude [Fischer B, Weber H (1992) in Exp Brain Res 89:415-424]. This paper presents an extended antisaccade task that investigates what information, if any, subjects extract from redundant cues and go signals. In Exp. 1, multiple saccade locations were introduced and the go signal specified the goal location. A redundant cue appeared, prior to the go signal, in the antisaccade goal location (valid) or in the alternative location on the same side (invalid). In Exp. 2, motivational value was assigned to the go signal. The use of multiple locations showed that subjects automatically extract irrelevant positional information from the cue, which affects the programming of subsequent correct and error saccades. When the cued location was also the goal location, antisaccade reaction times were significantly reduced. The results from Exp. 2 showed that subjects also extract information from the go signal. Errors made to a go signal associated with a higher monetary value were initiated significantly faster than those to a lower monetary value. This study has shown that the visual stimuli used in this antisaccade task do more than initiate orienting sets: Their properties can influence the programming of both accurate actions and errors.