Biology subjects

Klanke, J.-N.

Publications and source records attributed to Klanke, J.-N..

3 recordsLinked to original sources

bioRxiv2025

In pursuit of saccade awareness: Limited control and minimal conscious access to catch-up saccades during smooth pursuit eye movements.

Observers use smooth pursuit to track moving objects--like koi carp gliding through a pond. When positional errors accumulate, rapid catch-up saccades correct for them. Despite their abruptness, these saccades usually go unnoticed, creating the seamless experience of smooth tracking. We conducted three experiments to examine awareness and control of catch-up saccades (Experiment 1), the effect of training (Experiment 2), and of movement intention (Experiment 3). All experiments followed a similar protocol. On each trial, a target moved horizontally at one of three constant speeds (3-12 dva/s). Two horizontal stimulus bands with vertically oriented gratings appeared above and below the trajectory. These bands were rendered invisible during pursuit by rapid phase shifts (>60 Hz), but became visible when briefly stabilized on the retina--either by a catch-up saccade or its replayed retinal consequence--providing immediate, saccade-contingent visual feedback. Observers reported whether they had seen the stimulus bands (visual sensitivity) and whether they were aware of making a catch-up saccade (saccade sensitivity). Visual sensitivity was consistently higher in trials with a catch-up saccade, confirming that these movements reduce retinal motion and enhance visibility. Higher target speeds increased saccade rate, but observers struggled to control them consciously: Visual feedback and training had no effect on the ability to control catch-up saccades. Only suppression-instructions yielded a small reduction. Saccade sensitivity was near zero, even in trials with saccade-contingent feedback. Neither training nor intention improved awareness. Together, our data suggest a limited ability to control and a low level of sensorimotor awareness of catch-up saccades during pursuit. Significance statementSmooth pursuit eye movements allow us to track moving objects seamlessly, yet these movements are frequently interrupted by small, rapid corrective catch-up saccades. Despite their disruptive nature, observers rarely notice their own catch-up saccades. To address this conundrum, we used a novel paradigm employing a stimulus that remains invisible during pursuit but becomes visible when retinally stabilized by a catch-up saccade--providing saccade-contingent visual feedback to investigate conscious control and awareness of catch-up saccades during pursuit. Our data show that higher target speeds increased saccade rates, and observers were largely unable to modulate this rate--except for a slight reduction when explicitly instructed to pursue as smoothly as possible. Moreover, awareness remained low even with saccade-contingent feedback, and neither training nor intention improved it. Together, these findings suggest limited conscious control and low sensorimotor awareness of catch-up saccades during smooth pursuit.

neuroscience↗

bioRxiv2025

Microsaccades do not give rise to a conscious feeling of agency for their sensorimotor consequences in visual perception.

Feeling of agency (FoA)--the experience of controlling ones actions and their outcomes--has been widely studied for bodily movements. Here, we investigated if microsaccades--small ballistic eye movements--are equally characterized by FoA and if intention mediates this sense of control. We measured FoA via intentional binding, a perceived compression between an action and its effect. In our experiments, we presented a vertically oriented grating, rendered invisible during stable fixation by a rapid temporal phase shift (>60 Hz) that became visible when its retinal motion was slowed down by a microsaccade (active condition). The stimulus was embedded in a clock face and observers reported perceived stimulus timing in each trial. Perceived timing of microsaccade-contingent stimulus perception was compared to the replay of a previous microsaccades retinal consequence (replay condition). Trials without a stimulus were included as a control. To examine the role of intention, we tested this paradigm across two experiments in which observers were either instructed to saccade (intended microsaccades) or fixate (unintended microsaccades). In Experiment 2, no instruction was administered such that any microsaccades were considered spontaneous. Microsaccades--either actively generated or replayed-- consistently rendered the stimulus highly visible compared to trials without such movements-- provided microsaccade direction and peak velocity aligned with the stimuluss motion. Temporal estimates did not differ between the active and replay conditions for any microsaccade type. This result suggests the absence of temporal binding between eye movements and their sensory consequences, and that intention does not facilitate FoA for small eye movements. Significance statementEye movements reflect our decision to closer inspect an aspect of the environment--bodily actions that align our perception with a preceding intention. Here, we investigated if microsaccades--a ballistic, minuscule type of saccade--can be characterized by a feeling of agency: the faint experience of affecting change through intentional actions. In two experiments, we presented an identical stimulus whose visibility was either gaze-contingent (active condition) or independent of eye movements (replay condition). In Experiment 1, we directly compared intended and unintended microsaccades and contrasted them with spontaneous microsaccades in Experiment 2. We found no difference between the active and replay condition for either eye movement type. Our data, hence, does not support feeling of agency for microsaccades. While it remains an open question if large saccades are characterized by feeling of agency, our finding demonstrates that intention is not sufficient to elicit feeling of agency for minuscule motor acts.

neuroscience↗

bioRxiv2024

Sensorimotor awareness requires intention: Evidence from minuscule eye movements.

Microsaccades are tiny eye movements that are thought to occur spontaneously and without awareness but can also be intentionally controlled with high precision. We used these tiny visual actions to investigate how intention modulates sensorimotor awareness by directly comparing intended, unintended, and spontaneous microsaccades. In addition, we dissociated the effects of action intention and the actions visual consequences on awareness. In 80% of all trials, we presented a stimulus at high temporal frequency rendering it invisible during stable fixation. Critically, the stimulus became visible when a microsaccade in the same direction caused it to slow down on the retina (generated microsaccade condition; 40% of trials) or when the microsaccades visual consequence was replayed (replayed microsaccade condition; 40% of trials). Participants reported whether they perceived the stimulus (visual sensitivity), whether they believed they had made a microsaccade (microsaccade sensitivity), and their level of confidence that their eye movement behavior was linked to their perception (causality assignment). Visual sensitivity was high for both, generated and replayed microsaccades and comparable for intended, unintended, and spontaneous eye movements. Microsaccade sensitivity, however, was low for spontaneous microsaccades, but heightened for both intended and unintended eye movements, showing that the intention to saccade or fixate enhances awareness of otherwise undetected eye movements. Visual consequences failed to aid eye movement awareness, and confidence ratings revealed a poor understanding of a causal relationship between eye movement and sensory consequence. These findings highlight the functional relevance of intention in sensorimotor awareness at the smallest scale of visual actions. Significance statementWhile eye movements are among the most frequent human actions, they are rarely perceived consciously, despite causing sweeping changes in retinal inputs. Here investigate how intention can modulate awareness of even the smallest human actions: microsaccades. We developed a novel paradigm that allowed us to dissociate the role of action intention and an actions sensory consequence for awareness, two factors that previous research has typically confounded. Our data provide strong evidence that observers can detect small eye movements reliably and demonstrates that sensitivity towards microsaccades was neither driven by an eye movements motor component nor its visual consequences alone. Instead, we find that intention opens a gate to sensorimotor awareness, even for actions typically too small to be perceived.

neuroscience↗