Journal of Vision最新文献

The human visual system is continuously processing visual information to maintain a coherent perception of the environment. Temporal integration, a critical aspect of this process, allows for the combination of visual inputs over time, enhancing the signal-to-noise ratio and supporting high-level cognitive functions. Traditional methods for measuring temporal integration often require a large number of trials made up of a fixation period, stimuli separated by a blank interval, a single forced choice, and then a pause before the next trial. This trial structure potentially introduces fatigue and biases. Here, we introduce a novel continuous temporal integration (CTI) task designed to overcome these limitations by allowing free visual exploration and continuous mouse responses to dynamic stimuli. Fifty participants performed the CTI, which involved adjusting a red bar to indicate the point where a flickering sine wave grating became indistinguishable from noise. Our results, modeled by an exponential function, indicate a reliable temporal integration window of ∼100 ms. The CTI's design facilitates rapid and reliable measurement of temporal integration, demonstrating potential for broader applications across different populations and experimental settings. This task provides a more naturalistic and efficient approach to understanding this fundamental aspect of visual perception.

Manipulations of the strength of visual motion coherence have been widely used to study behavioral and neural mechanisms of visual motion processing. Here, we used a novel broadband visual stimulus to test how the strength of motion coherence in different spatial frequency (SF) bands impacts human ocular-following responses (OFRs). Synthesized broadband stimuli were used: a sum of one-dimensional vertical sine-wave gratings (SWs) whose SFs ranged from 0.0625 to 4 cpd in 0.05-log2(cpd) steps. Every 20 ms a proportion of SWs (from 25% to 100%) shifted in the same direction by ¼ of their respective wavelengths (drifting), whereas the rest of the SWs were assigned a random phase (flicker), shifted by half of their respective wavelengths (counterphase), or remained stationary (static): 25% to 100% motion coherence. As expected, the magnitude of the OFRs decreased as the proportion of non-drifting SWs and/or their contrast increased. The effects, however, were SF dependent. For flicker and static SWs, SFs in the range of 0.3 to 0.6 cpd were the most disruptive, whereas, with counterphase SWs, low SFs were the most disruptive. The data were well fit by a model that combined an excitatory drive determined by a SF-weighted sum of drifting components scaled by a SF-weighted contrast normalization term. Flicker, counterphase, or static SWs did not add to or directly impede the drive in the model, but they contributed to the contrast normalization process.

The fact that blinks occur more often than necessary for ocular lubrication has led to the proposal that blinks are involved in altering some aspects of visual cognition. Previous studies have suggested that blinking can modulate the alternation of different visual interpretations of the same stimulus, that is, perceptual alternation in multistable perception. This study investigated whether and how different types of blinks, spontaneous and voluntary, interact with perceptual alternation in a multistable perception paradigm called continuous flash suppression. The results showed that voluntary blinking facilitated perceptual alternation, whereas spontaneous blinking did not. Moreover, voluntary eye-widening, as well as eyelid closing, facilitated perceptual alternation. Physical blackouts, which had timing and duration comparable to those of voluntary blinks, did not produce facilitatory effects. These findings suggest that the effects of voluntary eyelid movements are mediated by extraretinal processes and are consistent with previous findings that different types of blinks are at least partially mediated by different neurophysiological processes. Furthermore, perceptual alternation was also found to facilitate spontaneous blinking. These results indicate that eyelid movements and perceptual alternation interact reciprocally with each other.

Much progress has been made in understanding how the brain combines signals from the two eyes. However, most of this work has involved achromatic (black and white) stimuli, and it is not clear if the same processes apply in color-sensitive pathways. In our first experiment, we measured contrast discrimination ("dipper") functions for four key ocular configurations (monocular, binocular, half-binocular, and dichoptic), for achromatic, isoluminant L-M and isoluminant S-(L+M) sine-wave grating stimuli (L: long-, M: medium-, S: short-wavelength). We find a similar pattern of results across stimuli, implying equivalently strong interocular suppression within each pathway. Our second experiment measured dichoptic masking within and between pathways using the method of constant stimuli. Masking was strongest within-pathway and weakest between S-(L+M) and achromatic mechanisms. Finally, we repeated the dipper experiment using temporal luminance modulations, which produced slightly weaker interocular suppression than for spatially modulated stimuli. We interpret our results in the context of a contemporary two-stage model of binocular contrast gain control, implemented here using a hierarchical Bayesian framework. Posterior distributions of the weight of interocular suppression overlapped with a value of 1 for all dipper data sets, and the model captured well the pattern of thresholds from all three experiments.

An attractive influence of past sensory experience on current behavior has been observed in many domains ranging from perceptual decisions to motor responses. However, it is unclear what sort of information is integrated across trials, especially for oculomotor behavior. Here we provide a detailed investigation of the spatial and directional tuning of serial dependence for oculomotor tracking. Across multiple experiments, we measured oculomotor responses to sequences of movements: the first movement (prior) could move at different velocities (5 deg/s or 15 deg/s), and could vary in its spatial location or direction relative to the following movement. The second movement (probe) was constant across all experiments and moved at 10 deg/s. We observed that eye velocity for the probe was faster when following the fast prior compared to following the slow prior, replicating attractive serial dependence. Importantly, this effect stayed consistent for distances of up to 30 deg between prior and probe, indicating a retinotopic reference frame. When we manipulated the direction of the prior, we observed that the influence of the prior on eye velocity, as well as eye direction, was stronger for prior directions more similar to the probe direction, and the magnitude of the effect on eye velocity and eye direction was correlated. Across all experiments, we observed that even when the prior moved in the opposite direction, there was a residual attractive effect. This suggests that serial dependence for oculomotor tracking consists of two components, one retinotopic, direction-tuned component and one more general component that is not direction specific.

Serial dependence effects have been observed across a wide range of perceptual and oculomotor tasks. This opens up the question of whether these effects observed share underlying mechanisms. Here we measured serial dependence effects in a semipredictable environment for the same group of observers across four different tasks, two perceptual (color and orientation judgments) and two oculomotor (tracking moving targets and the pupil light reflex). By leveraging individual differences, we searched for links in the magnitude of serial dependence effects across the different tasks. On the group level, we observed significant attractive serial dependence effects for all tasks, except the pupil response. The rare absence of a serial dependence effect for the reflex-like pupil light response suggests that sequential effects require cortical processing or even higher-level cognition. For the tasks with significant serial dependence effects, there was substantial and reliable variance in the magnitude of the sequential effects. We observed a significant relationship in the strength of serial dependence for the two perceptual tasks, but no relation between the perceptual tasks and oculomotor tracking. This emphasizes differences in processing between perception and oculomotor control. The lack of a correlation across all tasks indicates that it is unlikely that the relation between the individual differences in the magnitude of serial dependence is driven by more general mechanisms related to for example working memory. It suggests that there are other shared perceptual or decisional mechanisms for serial dependence effects across different low-level perceptual tasks.

Contrast sensitivity, the amount of contrast required to discriminate an object, depends on spatial frequency (SF). The contrast sensitivity function (CSF) peaks at intermediate SFs and drops at other SFs. The CSF varies from foveal to peripheral vision, but only a couple of studies have assessed how the CSF changes with polar angle of the visual field. For many visual dimensions, sensitivity is better along the horizontal than the vertical meridian and at the lower than the upper vertical meridian, yielding polar angle asymmetries. Here, for the first time, to our knowledge, we investigate CSF attributes around polar angle at both group and individual levels and examine the relations in CSFs across locations and individual observers. To do so, we used hierarchical Bayesian modeling, which enables precise estimation of CSF parameters. At the group level, maximum contrast sensitivity and the SF at which the sensitivity peaks are higher at the horizontal than vertical meridian and at the lower than the upper vertical meridian. By analyzing the covariance across observers (n = 28), we found that, at the individual level, CSF attributes (e.g., maximum sensitivity) across locations are highly correlated. This correlation indicates that, although the CSFs differ across locations, the CSF at one location is predictive of that at another location. Within each location, the CSF attributes covary, indicating that CSFs across individuals vary in a consistent manner (e.g., as maximum sensitivity increases, so does the corresponding SF), but more so at the horizontal than the vertical meridian locations. These results show similarities and uncover some critical polar angle differences across locations and individuals, suggesting that the CSF should not be generalized across isoeccentric locations around the visual field.

When catching a falling ball or avoiding a collision with traffic, humans can quickly generate eye and limb responses to unpredictable changes in their environment. Mechanisms of limb and oculomotor control when responding to sudden changes in the environment have mostly been investigated independently. Here, we investigated eye-hand coordination in a rapid interception task where human participants used a virtual paddle to intercept a moving target. The target moved vertically down a computer screen and could suddenly jump to the left or right. In high-certainty blocks, the target always jumped; in low-certainty blocks, the target only jumped in a portion of the trials. Further, we manipulated response urgency by varying the time of target jumps, with early jumps requiring less urgent responses and late jumps requiring more urgent responses. Our results highlight differential effects of certainty and urgency on eye-hand coordination. Participants initiated both eye and hand responses earlier for high-certainty compared with low-certainty blocks. Hand reaction times decreased and response vigor increased with increasing urgency levels. However, eye reaction times were lowest for medium-urgency levels and eye vigor was unaffected by urgency. Across all trials, we found a weak positive correlation between eye and hand responses. Taken together, these results suggest that the limb and oculomotor systems use similar early sensorimotor processing; however, rapid responses are modulated differentially to attain system-specific sensorimotor goals.

In visual perception, an effect known as surround suppression occurs wherein the apparent contrast of a center stimulus is reduced when it is presented within a higher-contrast surrounding stimulus. Many key aspects of visual perception involve surround suppression, yet the neuromodulatory processes involved remain unclear. Psilocybin is a serotonergic psychedelic compound known for its robust effects on visual perception, particularly texture, color, object, and motion perception. We asked whether surround suppression is altered under peak effects of psilocybin. Using a contrast-matching task with different center-surround stimulus configurations, we measured surround suppression after 25 mg of psilocybin compared with placebo (100 mg niacin). Data on harms were collected, and no serious adverse events were reported. After taking psilocybin, participants (n = 6) reported stronger surround suppression of perceived contrast compared to placebo. Furthermore, we found that the intensity of subjective psychedelic visuals induced by psilocybin correlated positively with the magnitude of surround suppression. We note the potential relevance of our findings for the field of psychiatry, given that studies have demonstrated weakened visual surround suppression in both major depressive disorder and schizophrenia. Our findings are thus relevant to understanding the visual effects of psilocybin, and the potential mechanisms of visual disruption in mental health disorders.

Humans use environmental context for facilitating object searches. The benefit of context for visual search requires learning. Modeling the learning process of context for efficient processing is vital to understanding visual function in everyday environments. We proposed a model that accounts for the contextual cueing effect, which refers to the learning effect of scene context to identify the location of a target item. The model extracted the global feature of a scene and gradually strengthened the relationship between the global feature and its target location with repeated observations. We compared the model and human performance with two visual search experiments (letter arrangements on a gray background or a natural scene). The proposed model successfully simulated the faster reduction of the number of saccades required before target detection for the natural scene background compared with the uniform gray background. We further tested whether the model replicated the known characteristics of the contextual cueing effect in terms of local learning around the target, the effect of the ratio of repeated and novel stimuli, and the superiority of natural scenes.