The spread of presaccadic attention depends on the spatial configuration of the visual scene

Ultra-fine resolution of pre-saccadic attention in the fovea

Microsaccades, the tiny gaze relocations that occurr during fixation, have been linked to covert attention deployed degrees away from the center of gaze. However, the link between attention and microsaccades is deeper in that it also unfolds at the foveal scale. Here, we have examined the spatial grain of pre-microsaccadic attention across the 1° foveola. Through the use of high-precision eye-tracking and gaze-contingent display system that achieves arcminute precision in gaze localization, we have shown that the spotlight of attention at this scale can reach a strikingly high resolution, in the order of 0.17°. Further, when a microsaccade occurs, vision is modulated in a peculiar way across the foveola; whereas fine spatial vision is enhanced at the microsaccade goal location, it drops at the very center of gaze, where acuity is normally highest. These results reveal the finesse of the visuomotor system and of the interplay between eye movements and attention.

Presaccadic attention does not facilitate the detection of changes in the visual field

Planning a rapid eye movement (saccade) changes how we perceive our visual world. Even before we move the eyes visual discrimination sensitivity improves at the impending target of eye movements, a phenomenon termed "presaccadic attention." Yet, it is unknown if such presaccadic selection merely affects perceptual sensitivity, or also affects downstream decisional processes, such as choice bias. We report a surprising lack of presaccadic perceptual benefits in a common, everyday setting-detection of changes in the visual field. Despite the lack of sensitivity benefits, choice bias for reporting changes increased reliably for the saccade target. With independent follow-up experiments, we show that presaccadic change detection is rendered more challenging because percepts at the saccade target location are biased toward, and more precise for, only the most recent of two successive stimuli. With a Bayesian model, we show how such perceptual and choice biases are crucial to explain the effects of saccade plans on change detection performance. In sum, visual change detection sensitivity does not improve presaccadically, a result that is readily explained by teasing apart distinct components of presaccadic selection. The findings may have critical implications for real-world scenarios, like driving, that require rapid gaze shifts in dynamically changing environments.

A dynamic 1/f noise protocol to assess visual attention without biasing perceptual processing

Psychophysical paradigms measure visual attention via localized test items to which observers must react or whose features have to be discriminated. These items, however, potentially interfere with the intended measurement, as they bias observers' spatial and temporal attention to their location and presentation time. Furthermore, visual sensitivity for conventional test items naturally decreases with retinal eccentricity, which prevents direct comparison of central and peripheral attention assessments. We developed a stimulus that overcomes these limitations. A brief oriented discrimination signal is seamlessly embedded into a continuously changing 1/f noise field, such that observers cannot anticipate potential test locations or times. Using our new protocol, we demonstrate that local orientation discrimination accuracy for 1/f filtered signals is largely independent of retinal eccentricity. Moreover, we show that items present in the visual field indeed shape the distribution of visual attention, suggesting that classical studies investigating the spatiotemporal dynamics of visual attention via localized test items may have obtained a biased measure. We recommend our protocol as an efficient method to evaluate the behavioral and neurophysiological correlates of attentional orienting across space and time.

Tactile motor attention induces sensory attenuation for sounds

Sensory events appear reduced in intensity when we actively produce them. Here, we investigated sensory attenuation in a virtual reality setup that allowed us to manipulate the time of tactile feedback when pressing a virtual button. We asked whether tactile motor attention might shift to the tactile location that makes contact with the button. In experiment one, we found that a tactile impulse was perceived as more intense when button pressing. In a second experiment, participants pushed a button and estimated the intensity of sounds. We found sensory attenuation for sounds only when tactile feedback was provided at the time the movement goal was reached. These data indicate that attentional prioritization for the tactile modality during a goal-directed hand movement might lead to a transient reduction in sensitivity in other modalities, resulting in sensory attenuation for sounds.

The effect of spatial structure on presaccadic attention costs and benefits assessed with dynamic 1/f noise

Already before the onset of a saccadic eye movement, we preferentially process visual information at the upcoming eye fixation. This 'presaccadic shift of attention' is typically assessed via localized test items, which potentially bias the attention measurement. Here we show how presaccadic attention shapes perception from saccade origin to target when no scene-structuring items are presented. Participants made saccades into a 1/f ('pink') noise field, in which we embedded a brief orientation signal at various locations shortly before saccade onset. Local orientation discrimination performance served as a proxy for the allocation of attention. Results demonstrate that (1) the presaccadic attention shift is accompanied by considerable attentional costs at the presaccadic eye fixation; (2) saccades are preceded by shifts of attention to their goal location even if they are directed into an unstructured visual field, but the spread of attention, compared to target-directed saccades, is broad; We conclude that the absence or presence of saccade target objects markedly shapes the distribution of presaccadic attention, and likely the underlying (space-based or object-based) cortical control mechanism. Our findings demonstrate the relevance of an item-free approach for measuring attentional dynamics across the visual field.

To look or not to look: dissociating presaccadic and covert spatial attention

Attention is a central neural process that enables selective and efficient processing of visual information. Individuals can attend to specific visual information either overtly, by making an eye movement to an object of interest, or covertly, without moving their eyes. We review behavioral, neuropsychological, neurophysiological, and computational evidence of presaccadic attentional modulations that occur while preparing saccadic eye movements, and highlight their differences from those of covert spatial endogenous (voluntary) and exogenous (involuntary) attention. We discuss recent studies and experimental procedures on how these different types of attention impact visual performance, alter appearance, differentially modulate the featural representation of basic visual dimensions (orientation and spatial frequency), engage different neural computations, and recruit partially distinct neural substrates. We conclude that presaccadic attention and covert attention are dissociable.

The peripheral sensitivity profile at the saccade target reshapes during saccade preparation

Goal-directed eye movements (saccades) bring peripheral objects of interest into high-acuity foveal vision. In preparation for the incoming foveal image, the perception of the saccade target may sharpen gradually before the eye movement is executed. Indeed, previous studies suggest that pre-saccadic attention shifts enhance sensitivity to high spatial frequencies (SFs) more than sensitivity to lower SFs. This pattern, however, was observed within a narrow frequency range and may reflect local changes in the shape of a broader underlying sensitivity profile. Depending on the development of the profile's shape, SFs above the previously examined range may profit less from saccade preparation. To assess the impact of saccade preparation on the shape of a broader sensitivity profile, we prompted observers to discriminate the orientation of a sinusoidal grating (the probe) presented briefly at the target of an impending saccade, at 10 dva (degree of visual angle) eccentricity. The probe's SF ranged from 1 to 5.5 cycles per dva (cpd) and was unpredictable on a given trial. We fitted observers' response accuracies across SFs with a log-parabolic, that is, inverted U-shaped function. Long before saccade onset, the profile peaked at .6 cpd and dropped off towards lower and higher SFs with broad bandwidth. During saccade preparation, the peak of the profile increased and shifted towards higher SFs while the bandwidth of the profile decreased. As a consequence of this reshaping process, pre-saccadic enhancement increased with SF up to 2.5 cpd, corroborating previous findings. Sensitivities to higher SFs, however, profited less from saccade preparation. We conclude that the extent of pre-saccadic enhancement to a particular SF is governed by its position on a broader sensitivity profile which reshapes substantially during saccade preparation. The shift of the profile's peak towards higher SFs increases resolution at the saccade target even when the features of relevant visual information are unpredictable.

Spatial Attention and Saccade Preparation Both Independently Contribute to the Discrimination of Oblique Orientations

The extent to which the preparation of an eye movement and spatial attention both independently influence performance within the same task has long been debated. In a recent study that combined computational modelling with a dual-task, both saccade preparation and spatial cueing were revealed to separately contribute to the discrimination of targets oriented along the cardinal axis (horizontal and vertical). However, it remains to be seen whether and to what degree the same holds true when different perceptual stimuli are used. In the present study, we combined evidence accumulation modelling with a dual-task paradigm to assess the extent to which both saccade preparation and spatial attention contribute to the discrimination of full contrast targets oriented along the oblique axis (diagonal). The results revealed a separate and quantifiable contribution of both types of orienting to discrimination performance. Comparison of the magnitude of these effects to those obtained for cardinal orientation discrimination revealed the influence of saccade preparation and spatial attention to be six times smaller for oblique orientations. Importantly, the results revealed a separate and quantifiable contribution of both saccade preparation and spatial attention regardless of perceptual stimuli or stimulus contrast.