The Effect of Stimulus Size and Eccentricity on Attention Shift Latencies

Differences between overt, covert and natural attention shifts to emotional faces

In daily life, individuals pay attention to emotional facial expressions and dynamically choose how to shift their attention, i.e. either overtly (with eye-movements) or covertly (without eye-movements). However, research on attention to emotional faces has mostly been conducted in controlled laboratory settings, in which people were instructed where to look. The current preregistered study co-registered EEG and eye-tracking to investigate differences in emotion-driven attention between instructed and uninstructed natural attention shifts in 48 adults. While a central stimulus was presented to the participant, a face appeared in the periphery, showing either a happy, neutral or an angry expression. In three counterbalanced blocks participants were instructed to either move their eyes overtly to the peripheral face, keep fixating the center and therefore covertly shift their attention, or freely look wherever they would like to look. We found that emotional content had stronger effects on the amplitude of the Early Posterior Negativity when participants shifted attention naturally, and that natural shifts of attention differed from instructed shifts in both saccade behavior and neural mechanisms. In summary, our results emphasize the importance of investigating modulation of attention using paradigms that allow participants to allocate their attention naturally.

Relation Between Event-Related Potential Latency and Saccade Latency in Overt Shifts of Attention

Controlled shifts of attention between competing stimuli are crucial for effective everyday visual behaviour. While these typically involve overt shifts of fixation, many past studies used covert attention shifts in which fixation is unchanged, meaning that some response components may result from the inhibition of eye movements. In this study, the neural events in the human brain when making overt shifts of attention are studied through the combination of event-related potential recording with simultaneous eye tracking. Fixation shifts under competition (central target remains visible when a peripheral target appears) were compared with noncompetition (central target disappears). A longer latency for competition compared with noncompetition, which is found in the saccadic response, is already present in the early occipital positivity when a single target is presented for the fixation shift. These results indicate that the requirement to disengage from a current target affects the time course of neural processing at an early level. However, the relation is more complex when the participant is required to choose which of two targets to fixate.

The Role of Perspective Taking on Attention: A Review of the Special Issue on the Reflexive Attentional Shift Phenomenon

Attention is a process that alters how cognitive resources are allocated, and it allows individuals to efficiently process information at the attended location. The presence of visual or auditory cues in the environment can direct the focus of attention toward certain stimuli even if the cued stimuli are not the individual’s primary target. Samson et al. demonstrated that seeing another person in the scene (i.e., a person-like cue) caused a delay in responding to target stimuli not visible to that person: “alter-centric intrusion.” This phenomenon, they argue, is dependent upon the fact that the cue used resembled a person as opposed to a more generic directional indicator. The characteristics of the cue are the core of the debate of this special issue. Some maintain that the perceptual-directional characteristics of the cue are sufficient to generate the bias while others argue that the cuing is stronger when the cue has social characteristics (relates to what another individual can perceive). The research contained in this issue confirms that human attention is biased by the presence of a directional cue. We discuss and compare the different studies. The pattern that emerges seems to suggest that the social relevance of the cue is necessary in some contexts but not in others, depending on the cognitive demand of the experimental task. One possibility is that the social mechanisms are involved in perspective taking when the task is cognitively demanding, while they may not play a role in automatic attention allocation.