Sites of overt and covert attention define simultaneous spatial reference centers for visuomotor response

Acute Itch Induces Attentional Avoidance of Itch-related Information

Attention is known to modulate itch intensity. In contrast, the reverse relationship, i.e. the degree to which the presence of an acute itch affects attention, is currently not well understood. The aims of this study were to investigate whether acute itch induces an attentional bias towards or away from visual itch-related stimuli, and if so, whether it occurs in the early or later stages of processing. A volunteer sample of 60 healthy individuals were subjected to a skin prick (either histamine or placebo), followed by completion of a spatial cueing paradigm using itch-related and neutral words as cues, in order to obtain reaction time estimates of attentional bias. The results suggest that experience of acute itch induces attentional avoidance of visual itch threats. This attentional avoidance occurs at a later processing stage in the form of facilitated disengagement of attention from itch and/or delayed disengagement from neutral information.

In pursuit of visual attention: SSVEP frequency-tagging moving targets

Previous research has shown that visual attention does not always exactly follow gaze direction, leading to the concepts of overt and covert attention. However, it is not yet clear how such covert shifts of visual attention to peripheral regions impact the processing of the targets we directly foveate as they move in our visual field. The current study utilised the co-registration of eye-position and EEG recordings while participants tracked moving targets that were embedded with a 30 Hz frequency tag in a Steady State Visually Evoked Potentials (SSVEP) paradigm. When the task required attention to be divided between the moving target (overt attention) and a peripheral region where a second target might appear (covert attention), the SSVEPs elicited by the tracked target at the 30 Hz frequency band were significantly, but transiently, lower than when participants did not have to covertly monitor for a second target. Our findings suggest that neural responses of overt attention are only briefly reduced when attention is divided between covert and overt areas. This neural evidence is in line with theoretical accounts describing attention as a pool of finite resources, such as the perceptual load theory. Altogether, these results have practical implications for many real-world situations where covert shifts of attention may discretely reduce visual processing of objects even when they are directly being tracked with the eyes.

Revealing the Radial Effect on Orientation Discrimination by Manual Reaction Time

It has been shown that the sensitivity and accuracy of orientation perception in the periphery is significantly better when the orientations are radial with respect to the fixation point than when they are tangential. However, since perception and action may be dissociated, it is unclear whether the perceptual radial effect has a counterpart in reaction time (RT) of motor responses. Furthermore, it is unknown whether or how stimulus-response-compatibility (SRC) effect interacts with the radial effect to determine RT. To address these questions, we measured subjects' manual RT to grating stimuli that appeared across upper visual field (VF). We found that (1) RTs were significantly shorter when a grating was oriented closer to the radial direction than when it was oriented closer to the tangential direction even though the perceptual accuracies for the more radial and more tangential orientations were not significantly different under our experimental condition; (2) This RT version of the radial effect was larger in the left VF than in the right VF; (3) The radial effect and SRC effect interacted with each other to determine the overall RT. These results suggest that the RT radial effect reported here is not a passive reflection of the radial effect in perceptual accuracy, but instead, represents different processing time of radial and tangential orientations along the sensorimotor pathway.