The reverse motion illusion in random dot motion displays and implications for understanding development

Across two independent developmental labs, we have been puzzled by the observation that a small proportion of our child and adult participants consistently report perceiving motion in the direction opposite to that presented in random dot motion displays, sometimes even when the motion is at 100% coherence. In this review, we first draw together existing reports of misperceptions of motion direction in random dot displays across observers in a small percentage of trials, before reporting evidence of consistent reverse motion perception in a minority of observers, including previously unreported observations from our own studies of visual development. We consider possible explanations for this reverse motion illusion, including motion induction, motion energy, correspondence noise and spatial undersampling. However, more work is required to understand the individual differences relating to this percept. We suggest that errors in perceived motion direction are likely to be more widespread than can be currently gleaned from the literature and explain why systematic study is needed, especially in children. Finally, we list some remaining open questions and call for collaborative efforts to document this phenomenon and stimulate future investigation.

The perceived position of a moving object is reset by temporal, not spatial limits

When the internal texture of a Gabor patch drifts orthogonally to its physical path, its perceived motion deviates dramatically from its physical path. The local position shifts accumulate to such an extent that a 45 deg oblique physical path appears to be vertical. However, at some point, a limit is reached and the path resets back to its veridical location, whereupon a new accumulation starts, making the new perceived path segment appear parallel to the pre-reset segment, but offset horizontally from it. Here, we tested whether spontaneous resets of this motion-induced position shift depend on the time or the distance over which position errors accrue, or both. We introduced a temporal gap in the middle of the path that forced the illusory path to reset back to its veridical physical position. This gap-triggered reset allowed us to measure the magnitude of the illusory offset up to that point. We found that perceived offset was less than expected for the angle of illusory drift, indicating that spontaneous resets had occurred prior to the gap-induced reset. The position offset decreased when the pre-gap duration increased but approximately doubled when the path length doubled. This pattern of perceived offsets is best accounted for by spontaneous resets that occur randomly over time at a constant rate, independently of the distance traveled. Our results suggest a temporal, not spatial, limit for the accumulation of position errors that underlies this illusion.

Simulating musical rotation, contour and notes: perception of (e)motion in nonmusicians

The meaning of music may rely upon perceived motion (Zuckerkandl, 1971). Recently, the framework of embodied music cognition, which draws on the discovery of mirror neurons and the theory of embodied simulation (Gallese, 2007), makes the claim that our understanding of human-made sounds draws upon our experience of making the same or similar movements and sounds, which involves imitation of the source of visual and auditory information (Cox, 2011). This paper investigates perceived motion and embodied music experience in non-musicians across three musical dimensions: melodic contour (ascending, descending and flat), melodic complexity (low, medium, high) and, following from Hanson and Huron (2019), note pattern (binary, ternary, quaternary). As part of an initiative to adhere to a high aesthetic standard, 27 ten-second piano tracks were created in collaboration with a film composer. In the computer task, participants rated stimuli on a Visual Analogue Scale (VAS) ranging from 0 to 100 for perceived Direction, Rotation, Movement, and Emotional and Physical Involvement. Results showed that: 1) Quaternary conditions were perceived as having significantly more Rotation, Movement and being more Physically Involving than Ternary and Binary, 2) High Complexity conditions were perceived as evoking significantly more Movement and being more Emotionally Involving than Low and Medium, and 3) Ascending conditions were perceived as having significantly more Movement, Rotation and being more Emotionally and Physically Involving than Descending and Flat. Results indicate that greater embodiment evoked by musical ascent may be modulated by greater perceived exertion or ‘effort’ to reach higher pitches, in line with the mimetic subvocalization hypothesis (Cox, 2017). Future studies are needed to investigate whether perceived rotation is driven by note pattern (i.e. metre) or note density and pitch., and how musical contour and rotation impact sensorimotor activation in the brain.

Revisiting the Perceived Motion Model that Predicted 360 FPS Displays by S Daly 2021

A previous model of motion perception used in engineering display design predicted the need for a 360 FPS (frames per second) and 1080-line display and image signal format system, in order to match the viewing of reality. Now that 360 FPS gaming monitors are on the market, the model is revisited with twenty years of new studies, display technology advancements such as HDR (high dynamic range), and inclusion of new viewing tasks such as performance gaming. This revised model is then used to make new predictions for display and signal format requirements to achieve distortion-free viewing of reality and synthetic signals that do not impose limits to human performance.

The Role of Blinks, Microsaccades and their Retinal Consequences in Bistable Motion Perception

Eye-related movements such as blinks and microsaccades are modulated during bistable perceptual tasks. However, if they play an active role during internal perceptual switches is not known. We conducted two experiments involving an ambiguous plaid stimulus, wherein participants were asked to continuously report their percept, which could consist of either unidirectional coherent or bidirectional component movement. Our main results show that blinks and microsaccades did not facilitate perceptual switches. On the contrary, a reduction in eye movements preceded the perceptual switch. Blanks, on the other hand, thought to mimic the retinal consequences of a blink, consistently led to a switch. Through the timing of the blank-introduced perceptual change, we were able to estimate the delay between the internal switch and the response. This delay further allowed us to evaluate that the reduction in blink probability co-occurred with the internal perceptual switch. Additionally, our results indicate that distinct internal processes underlie the switch to coherent vs. component percept. Blanks exclusively facilitated a switch to the coherent percept, and only the switch to coherent percept was followed by an increase in blink rate. In a second study, we largely replicated the findings and included a microsaccade analysis. Microsaccades only showed a weak relation with perceptual switches, but their direction was correlated with the perceived motion direction. Nevertheless, our data suggests an interaction between microsaccades and blinks by showing that microsaccades were differently modulated around blinks compared with blanks. This study shows that a reduction in eye movements precedes internal perceptual switches indicating that the rate of blinks can set the stage for a reinterpretation of sensory input. While a perceptual switch based on changed sensory input usually leads to an increase in blink rate, such an increase was only present after the perceptual switch to coherent motion but absent after the switch to component percept. This provides evidence of different underlying mechanism or internal consequence of the two perceptual switches and suggests that blinks can uncover differences in internal percept-related processes that are not evident from the percept itself.

SUBJECTIVE VESTIBULAR TEST FINDINGS IN INDIVIDUALS WITH MOTION SICKNESS

Introduction: Motion Sickness (MS) is one among the most common distressing ailment accompanied with both actual and perceived motion. Regardless of its commonality, very little is known about the underlying pathophysiology. Several tests have proved the involvement of vestibular system in motion sickness. However, there is dearth of knowledge on the expected ndings of Subjective Vestibular Tests (SVT) in individuals with MS. Aim: To compare the SVT ndings in individuals with and without MS. Methodology:Recruited participants were divided into two groups. The group Aconsisted of participants experiencing symptoms of motion sickness and group B consisted of normal controls. To full the aim of the study, subjects were introduced to SVT such as Romberg's Test, Fukuda Stepping Test (FST), Gait Test, Subjective Visual Vertical (SVV) and Subjective Visual Horizontal (SVH). Results and Discussion:The results of the study depicted a good contribution of tests in identifying the affected vestibular system in individuals with MS. Further, about 55% abnormal test ndings in eyes open position for SVV test and 50% for SVH test were obtained. Similarly, eyes closed position yielded abnormal test ndings of 35% and 20% in FST and Gait test respectively. Finally, upon comparison between the test ndings, FST has been situated superior over other SVTs.The recruited tests are known to detect comparatively weaker labyrinth (not necessarily side of lesion) by the observed deviation from the start point in eyes open and closed position. The test results obtained beyond the normative values inherit the presence of otolithic end organ dysfunction in the vestibular system. Therefore, the individuals with MS nd it difcult to maintain the expected vertical and horizontal tilt.

Scrambling the skin: A psychophysical study of adaptation to scrambled tactile apparent motion

An age-old hypothesis proposes that object motion across the receptor surface organizes sensory maps (Lotze, 19th century). Skin patches learn their relative positions from the order in which they are stimulated during motion events. We propose that reversing the local motion within a global motion sequence (‘motion scrambling’) provides a good test for this idea, and present results of the first experiment implementing the paradigm. We used 6-point apparent motion along the forearm. In the Scrambled sequence, two middle locations were touched in reversed order (1-2-4-3-5-6, followed by 6-5-3-4-2-1, in a continuous loop). This created a double U-turn within an otherwise constant-velocity motion, as if skin patches 3 and 4 physically swapped locations. The control condition, Orderly, proceeded at constant velocity at inter-stimulus onset interval of 120 ms. The 26.4-minute conditioning (delivered in twenty-four 66-s bouts) was interspersed with testing of perceived motion direction between the two middle tactors presented on their own (sequence 3–4 or 4–3). Our twenty participants reported motion direction. Direction discrimination was degraded following exposure to Scrambled pattern and was 0.31 d’ weaker than following Orderly conditioning (p = .007). Consistent with the proposed role of motion, this could be the beginning of re-learning of relative positions. An alternative explanation is that greater speed adaptation occurred in the Scrambled pattern, raising direction threshold. In future studies, longer conditioning should tease apart the two explanations: our re-mapping hypothesis predicts an overall reversal in perceived motion direction between critical locations (for either motion direction), whereas the speed adaptation alternative predicts chance-level performance at worst, without reversing.