Scholte & de Hann (2025) have recently argued that there is no need to integrate information about different types of visual feature - the so-called visual binding problem. Here I argue that they are mistaken, and have ignored key evidence.
Recent studies in the perception of visual illusions as well as mental imagery indicate that adjustments of the eye pupils reflect the perception instead of the light input stimulating the eyes. The present study put to test the expectation that similar adjustments of the eye pupil and, possibly, of other oculomotor responses like vergence, would be triggered by the stereokinetic effect, that is, illusory depth. In an eye-tracking study, both gaze direction and pupillary changes were measured while observers viewed "rotoreliefs,"' that is, rotating two-dimensional patterns, that are known to generate a particularly strong impression of depth. Rotoreliefs can be multistable, and in some cases their perceptual interpretations alternate between seeing either a bump or a hole, protruding or extending beyond the screen. We found strong evidence that pupil diameters were larger when the depth illusion was that of a hole (funnel) than of a bump (cone). Additionally, eyes diverged a few seconds after observers reported a reversal from a bump to a hole. Thus, the eyes adjust spontaneously to what looks like a three-dimensional form, regardless of whether this is an illusion or a veridical perception. We propose that such oculomotor adjustments to illusions index the disambiguation of visual input that optimizes possible interactions with external objects in a dynamic 3D world.
Previous research has found that increased contrast between the skin and adjacent surfaces (e.g., eyebrows, eyes, and lips) makes the skin appear more even. In this study, we aimed to examine whether this effect can be extended to another ecologically significant situation—the contrast between the facial skin and the surfaces surrounding the face, whether background color or hair color. In two experiments, we found that the same faces were rated as having more even skin when surrounded by a black background versus a skin-colored background in Study 1 and that the same faces were rated as having more even skin when hair color was decreased in lightness versus increased in lightness in Study 2. Many practices of grooming and personal decoration involve surfaces adjacent to the skin, and our results provide evidence that these social practices have perceptual consequences related to skin appearance.
In this project, we investigate how visual complexity and the authorship of artworks, whether created by a human or modified by artificial intelligence, affect viewers' aesthetic experience. Additionally, we examine how these factors influence participants' evaluations of how beautiful and how intriguing they find the artworks. 71 participants viewed and evaluated 16 artworks drawn from an existing database, including original paintings and images modified by Neural Style Transfer. Using repeated-measures multivariate analysis of variance, we found significant main effects of complexity and authorship on aesthetic experience, as well as a significant interaction between these factors. Separate analysis of variances showed that higher complexity increased both beauty and intrigue ratings, while the main effect of image authorship on these dimensions was not significant. For beauty, this effect was further qualified by an interaction with authorship: among highly complex images, artificial intelligence (AI)-modified artworks were rated as more beautiful than original ones. Overall, these findings underline the central role of visual complexity in shaping aesthetic experience, as well as ratings of beauty and intrigue. Participants also reported higher ratings for original artworks compared to AI-modified images on selected dimensions of aesthetic experience including ease of perceptual organization, understanding, knowledge about the artwork and insight into the artist's intention. Notably, in AI-modified images, higher complexity enhanced perceptual clarity, understanding as well as perceived beauty, suggesting that aesthetic appreciation depends not only on perceptual fluency but also on meaningful structure and interpretability. Together, these findings highlight complementary effects of visual complexity and artwork authorship on subjective aesthetic experience.
Approximate numerosity judgments allow humans and animals to quickly estimate quantities without verbal processing. This ability obeys Weber's law, which states that the discrimination between two quantities depends on their ratio rather than their absolute difference, making numerosity perception robust across varying contexts. Despite its robustness, temporal constraints significantly influence numerosity judgments. Shorter response times have been associated with numerical overestimation; however, the consistency of this effect across different reference quantities and varying temporal demands remains unclear. To investigate this, an externally cued response-onset paradigm with cue delays ranging from 60 to 1000 ms was employed across four reference numbers (30, 40, 50, and 60), with comparison stimuli standardized by proportionally scaled numerical differences corresponding to one-fifth of each reference number. Comprehensive analysis methods were used, including relative bias and reaction time analysis, signal detection theory, and Bayesian psychometric modeling to examine changes in normalized perceived numerosity, sensitivity, and decision-making biases. The analyses revealed that shorter response onsets (60 and 120 ms) systematically yield an overestimation bias, which is associated with a liberal decision criterion and low sensory precision. Furthermore, posterior distributions indicated that as processing time increases, sensory evidence becomes more stable, thereby increasing the precision of numerical judgments. Crucially, this temporal effect was consistent across all reference conditions, suggesting that the approximate number system (ANS) operates in a ratio-sensitive manner independent of absolute quantity. These findings deepen the understanding of the ANS by showing how temporal constraints work with ratio-based processing, providing an extended behavioral approach for investigating the dynamic, scale-invariant nature of numerical cognition.
Sensory events associated with motor actions are critical for perceptual calibration and motor control. Due to the stable temporal relationships between these events, individuals can anticipate the timing of one event based on another. While temporal expectancy is well-established for supraliminal stimuli (conscious cues) through temporal orienting, less is known about the role of subliminal cues generated by actions. Although subliminal stimuli are known to influence perception and behavior-specifically in forming spatial expectancies-their role in temporal expectancy remains unclear. Furthermore, evidence suggests that prior supraliminal experience may enhance the utilization of subliminal information. Integrating the conceptual link between space and time, the present study investigated whether individuals can form temporal expectancies based on action-generated subliminal stimuli and explored how supraliminal experience modulates this process. Our results indicate that participants do not form temporal expectancies through subliminal cues alone. Instead, the formation of such expectancy and transferred learning benefits upon target discrimination (i.e., orientation discrimination) depends on prior supraliminal experience with the association between the cue and the temporal onset of the subsequent target.
The tactile perception of wet fabrics plays an important role in human comfort, but the underlying mechanisms of skin-wet fabric interaction remain unclear. This study measured the basic properties (saturated water content, wicking height, moisture regain rate, fabric density, and yarn diameter) of 20 fabrics, collected real-time tactile physical parameters (skin cooling rate, normal pressure, frictional coefficient, maximum acceleration amplitude, and acceleration mean square deviation), and subjective tactile perception ratings (wetness, coldness, roughness, stiffness, and total hand feeling value) during the interactions between fingertip and fabrics with three relative water contents (dry, 35%, and 70% saturated water content). The results demonstrated the significant effects of fabric water content on tactile perceptions and tactile physical parameters. Four machine learning methods, Gradient Boosting Regression, XGBoost Regression, Random Forest Regression, Artificial Neural Networks Regression (ANNR), and a linear regression method, Partial Least Squares Regression, were used to establish predictive models. The ANNR model demonstrated the best performance in total hand feeling value (R2 = 0.727, root mean square error = 0.66), and SHapley Additive exPlanations analysis revealed eight key factors, highlighting the significant effect of fabric water content and mechanical stimulation on total hand feeling value. These findings provide deeper insights into enhancing the comfort of wet textiles and offer potential guidance to optimize the tactile design of products.
Two-frame motion defined form is a type of discontinuous motion contrast rendering objects visible through short distance displacement of a region within two otherwise identical sequentially presented random-dot patterns. The resulting illusory object is transiently perceived before fading. The purpose of this study was to benchmark visual spatial acuity for two-frame motion defined form compared to luminance and disparity defined forms. Random dot patterns of equal dot density were used for all contrast types to ensure equivalence of spatial sampling. Stimulus durations in the luminance and stereoscopic conditions were set at the subjective duration (∼270 ms) of the two-frame motion defined form measured in a control experiment. In the main experiment, 25 participants made forced choice judgements on the aspect ratios of the target defined by each of the contrasts using the method of constant stimuli. Participants indicated whether the target square was 'wider' or 'taller' as a function of the aspect ratio of the target while controlling for trial-to-trial variations in the distance between the vertical/horizontal edges of the target and the boundaries of the surrounding dots. Group mean just-noticeable differences (JNDs) for luminance and stereoscopic conditions translated to changes in aspect ratio of 4.8% and 4%, respectively. They were significantly smaller than the two-frame motion defined condition, 5.8%. Spatial acuity for two-frame motion defined forms is only slightly inferior to other contrast types when equated for spatial sampling and duration. This study is the first benchmark of visual acuity for two-frame motion defined form against luminance and disparity defined form.
Facial expressions play a crucial role in social communication, influencing judgments of trustworthiness and competence. While previous research has examined how face masks affect trust and competence in general populations, little is known about their impact on individuals with high autistic traits, who often rely more on the mouth region for social cue interpretation. The present study investigates the effects of face masks on perceptions of trustworthiness and competence as a function of high and low autistic traits. Results show that masked faces are generally perceived as more trustworthy and competent than unmasked faces. The effect of mask wearing on trustworthiness and competence ratings was not affected by autistic traits, suggesting that participants, regardless of their level of autistic traits, adjusted their judgements using available facial cues.
Alexithymia, a personality trait marked by difficulty in identifying and describing emotions, is associated with differences in interoception - the ability to perceive and interpret internal bodily signals. Interoception plays a key role in forming a coherent sense of self and contributes to body ownership, the feeling that one's body belongs to oneself. This study explored how interoception and alexithymia influence body ownership in immersive virtual reality, particularly under conditions of motor cue congruency. Findings revealed a negative relationship between alexithymia and interoception, and a positive effect of motor synchrony on body ownership. Interoceptive accuracy (assessed via the heartbeat counting task) showed a trend-level positive association with body ownership when virtual and physical movements were aligned. Given the modest sample size (N = 26) and reliance on a single cardiac interoceptive measure, findings should be considered preliminary and warrant replication in larger, multi-method studies.
Emotional states influence taste perception, yet the knowledge to fully explain this phenomenon remains insufficient. This study investigated this influence in two parts: Experiment 1 focused on the effects of valence and arousal based on the circumplex model of emotions, while Experiment 2 explored a possible mechanism behind valence effects through semantic priming. In Experiment 1, four emotional states were assumed based on valence (positive-negative), arousal (high arousal-low arousal), and taste intensity was measured after evoking each state using video stimuli. In Experiment 2, we investigated the possibility that the influence of emotional valence on taste perception occurs through semantic priming mediated by the association between emotion-taste concepts. Initially, a cognitive task was conducted to modulate the strength of participants' conceptual associations between emotions and taste qualities. Subsequently, the effect on taste perception following the presentation of either positive or negative auditory stimuli was examined. The results confirmed that emotional valence, rather than arousal, influences the intensity of sweetness and bitterness. Consistent with prior research, the study also verified that the patterns of taste perception change due to emotional states differ between sweetness and bitterness. In particular, the perception of bitterness was found to be intensified by negative emotion through semantic priming, which is mediated by a conceptual association between negative emotion and bitterness.
