Martin Rolfs

Saccadic eye movements sweep objects across the retina at high speed, and this motion is routinely omitted from conscious perception. Whether object identity survives such motion is unclear. In two preregistered experiments (N = 20 and N = 19), we asked how object motion at saccadic speeds, while the eyes fixate, affects object continuity in the object-reviewing paradigm (Kahneman et al., 1992; Sasi et al., 2023). Two Gabor patches each carried a digit, then disappeared and reappeared in place, reappeared displaced, or travelled continuously to their new locations; the intervening interval lasted 300 ms or was matched to the mean or peak speed of a saccade. A target digit then appeared in one patch, and participants identified it. At the long duration, we replicated the Object-Specific Preview Benefit (OSPB): responses were faster when the target had been previewed in that same object than in the other one. At saccadic durations, the OSPB disappeared, and adding a distinguishing surface feature in Experiment 2 did not restore it. The general preview benefit, faster responses to any previewed digit than to a new one, persisted at every duration. Object features therefore survive motion at saccadic speed, but their link to a particular object does not.

Humans execute rapid saccadic eye movements to inspect objects of interest in high-acuity foveal vision. Even though each saccade entails a large-scale displacement of the retinal image, vision is continuous, and we easily keep track of the location and identity of relevant stimuli. Here, we highlight the contribution of predictive foveal processing to visual continuity. Specifically, we summarize evidence that foveal and even foveolar vision is nonuniform and modulated by attentional allocation. We then describe a set of psychophysical and neuroimaging studies demonstrating that defining features of the eye movement target are predicted in presaccadic foveal vision. We explore a parsimonious implementational mechanism and propose the contribution of foveal prediction to several seemingly unconnected phenomena that may be unified under a straightforward assumption: Peripheral saccade target features predictively alter feature tuning in high-acuity foveal vision, facilitating a smooth perceptual transition once the target shifts to the center of gaze.

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 volitionally: 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 awareness of catch-up saccades during pursuit.

Saccades made during memory maintenance prioritize memory for the saccade target, but it is unclear if this benefit is specific to a location or extends across memorized objects. In three experiments, we examined whether saccadic selection spreads to other locations within the same object. In Experiment 1, we asked observers to remember three oriented Gabors presented either within contour-defined objects or without object structure. A subsequent movement cue prompted observers to move their eyes to the indicated location. We then probed memory for stimuli at locations equidistant from the saccade target, in either the same or a different object. Memory was best for stimuli at locations congruent with the saccade target, and consistently weaker for other stimuli presented in the same or a different object than the saccade target. In Experiment 2, we created more complex objects by adding more object features to the stimulus. Again, memory performance was best for stimuli congruent with the saccade target location, whereas memory in incongruent trials was worse and similar for stimuli in the same and different object as the saccade target. In Experiment 3, we tested if saccadic selection is present and propagates within the object in a change detection task. Again, memory performance (i.e., change detection) was best at the saccade target location. However, this memory benefit also spread to other locations within the same object. Our results imply that saccadic selection in visual working memory is primarily space-based but can also spread towards locations within the object where a saccade was directed.

When one object approaches another object which, upon touching, moves in the same direction, humans report a vivid impression of one launching the other. Visual adaptation can alter this perception of causality: observers less often report seeing a launch after viewing a stream of launch events. In three experiments, we further characterised how visual adaptation influences the perception of causality by determining the spatial specificity of adaptation and timecourse of recovery from adaptation. In Experiment 1, observers saw ambiguous test events (i.e., the overlap between the two objects varied over trials) at three different horizontal eccentricities. Adaptation was strongest when adaptor and test event were presented at the same eccentricity, and absent when the two were separated by just three degrees of visual angle. Moreover, the perception of causality gradually recovered from adaptation, but remained incomplete. In Experiment 2, both long and short adaptation sequences were highly effective in driving adaptation, and showed no difference in the recovery timecourse, which was complete following more experimental blocks. In Experiment 3, a break without any task-relevant visual input also led to a recovery over the same timespan, but this time, the recovery was instantaneous and incomplete. Altogether, our results provide evidence for highly spatially specific computations, instananeously responding to the onset of adaptation and then gradually recovering from the adaptation over a short time window.

Saccadic eye movements sweep the visual scene across the retina, yet the resulting motion is rarely perceived. Visual factors alone, such as the presence of static pre- and post-saccadic images, can attenuate motion perception, suggesting a masking of the motion signal during early visual processing. Here, we isolated the visual component of this reduction in motion perception using simulated saccades presented to fixating observers. Across two experiments, we manipulated motion amplitude (6–18 dva), duration, and velocity profile and measured perceived amplitude and velocity at varying masking durations. Visual masking strongly reduced perceived motion amplitude and velocity, with short halftimes (∼15 ms) that were largely invariant across saccade amplitudes. Critically, motion following a naturalistic saccadic velocity profile was perceived as smaller and slower than constant-velocity motion matched in amplitude and duration, even without explicit masking. This additional reduction increased with both amplitude and duration. These results show that visual mechanisms alone can account for substantial motion reduction across a large range of amplitudes and demonstrate a partially separable contribution of the saccadic velocity profile, suggesting that the temporal structure of retinal motion itself supports perceptual continuity across eye movements.

Humans typically perceive their visual world as stable and continuous, despite frequent shifts of the retinotopic reference frame caused by saccades. This perceptual stability is paralleled by afterimage movement across saccades: Although retinotopically stable, afterimages appear to move in egocentric space wherever the eye moves. To investigate the mechanisms underlying this phenomenon, we tasked human observers to localize afterimages relative to briefly flashed probes in complete darkness. This psychophysical tracking of afterimages was accompanied by eye tracking, allowing us to fit a dedicated computational model to accurately predict afterimage movement based on the size of eye movements. The gain of afterimage movement was significantly hypometric, remained unaffected by postsaccadic visual feedback and saccadic adaptation, and was inversely related to saccade gain. Assuming a parsimonious framework of head-centered localization, afterimage movement is driven by efference-based, feedforward predictions of visual consequences of saccades, demonstrating the phenomenon’s usefulness for studying perceptual stability.

Sudden environmental changes can render planned hand movements suboptimal or even counterproductive. To prevent the execution of outdated motor plans, the motor system may transiently inhibit actions following salient changes, allowing time to evaluate alternatives. While such a mechanism is well established for eye movements, its applicability to hand movements remains unclear. Here, we present findings from three online behavioral experiments and two lab-based replications designed to probe key features of this mechanism in manual responses: reflexive inhibition, temporal precedence, complete movement updating, and sensitivity to saliency. Participants of either sex performed rapid sequential tapping movements toward onscreen targets. At an unpredictable time, either a relevant change (a target displacement) or an irrelevant change (a brief luminance flash) occurred. We measured movement initiation rates following these changes and compared them with a no-change baseline. A significant transient inhibition of movement initiation followed both relevant and irrelevant changes. This inhibition preceded observable updates to the movement plan. At the time of inhibition release, the update to a movement plan was complete. Across experiments, we observed stronger inhibitory effects for more salient changes. The lab-based replication confirmed that the latency of this inhibitory response aligns with visuomotor reaction times. These results support the existence of a general-purpose, rapid inhibitory mechanism in hand movements analogous to inhibition in the oculomotor system. We propose that such inhibition provides a reflexive, domain-general safeguard against obsolete actions following unexpected changes.

Human vision is characterized by frequent eye movements and constant shifts in visual input, yet our perception of the world remains remarkably stable. Here, we directly demonstrate image-specific foveal feedback to primary visual cortex in the context of saccadic eye movements. To this end, we used a gaze-contingent fMRI paradigm, in which peripheral saccade targets disappeared before they could be fixated. Despite no direct foveal stimulation, we were able to decode peripheral saccade targets from foveal retinotopic areas, demonstrating that image-specific feedback during saccade preparation may underlie this effect. Decoding was sensitive to shape but not semantic category of natural images, indicating feedback of only low-to-mid-level information. Cross-decoding to a control condition with foveal stimulus presentation indicates a shared representational format between foveal feedback and direct stimulation. Moreover, eccentricity-dependent analyses showed a U-shaped decoding curve, confirming that these results are not explained by spillover of peripheral activity or large receptive fields. Finally, fluctuations in foveal decodability covaried with activity in the intraparietal sulcus, thus providing a candidate region for driving foveal feedback. These findings suggest that foveal cortex predicts the features of incoming stimuli through feedback from higher cortical areas, which offers a candidate mechanism underlying stable perception.