Stimulus Speed Research Articles

Latent encoding of movement in primary visual cortex.

Cortical maps are thought to be useful for efficient processing of sensory information. In the primary visual cortex (V1), they are believed to provide uniform coverage across the visual field, ensuring that all orientations, spatial frequencies, and other features are consistently represented at each location in visual space. This organization supports stable visual perception, but it remains unclear how V1 encodes motion, particularly speed. Here, we reveal that cat V1 represents motion speed in a distributed manner without spatially organized temporal frequency maps, and that direction maps vary with stimulus speed. Nonetheless, we show that information on speed and preferred direction is decodable at all cortical locations. These findings challenge the classical uniform coverage hypothesis for motion attributes, and suggest that V1 encodes motion information in a more flexible manner.

Stereomotion Scotomas: An impairment of velocity-based mechanisms revealed by variation of stimulus speed

Stereomotion Scotomas: An impairment of velocity-based mechanisms revealed by variation of stimulus speed

Development of Dynamic Contrast Sensitivity Chart.

Dynamic visual acuity (DVA) is a complex visual function that requires the observer to detect a moving target, to visually acquire it by eye movements, and to resolve critical details contained in it, in a relatively brief time exposure. Dynamic contrast sensitivity (DCS) functions are determined over a range of angular velocities to complement the traditional contrast sensitivity (CS) functions (obtained with stationary targets). A new chart is constructed to assess DCS by chosen 5×5 grid and Sloan letters (D, H, N, U, V, R, Z, S, K, O, C). Letters are constructed at a constant visual acuity of six lines having the contrast varied at each interval of the line. Each line has six letters and each line subtends different contrast (0.20 logCS-1.70 logCS). The chart has a motor of 45 revolutions per minute (rpm) and 30 rpm and measured among the normal population of the age group of 17 to 30. Results shows that CS declines once the target stimulus is in motion. There was a statistically significant difference (p < 0.05) between the stimulus speeds of 30 rpm and 45 rpm. Dynamic contrast sensitivity values increased for lower target velocity indicating that as speed of the target stimulus increases, CS decreases. This study concludes that the DCS decreases as the velocity increases. Consequently, incorporating the DCS chart into comprehensive eye examinations provides a holistic understanding of an individual's visual function.

The poetry of psychological distance: Bidirectional associations between stimulus speed and its psychological distance and construal level.

Based on the cognitive-ecological approach and on logical-functional principles, in 12 studies (11 preregistered), we examine the novel hypotheses that psychological distance and construal level (CL) are associated in people's minds with stimulus speed: the psychologically distant/abstract is slow, and the psychologically close/concrete is fast. The findings support our expectations. Study Set I examined the association between psychological distance and speed. Findings show that psychological distance is implicitly and explicitly associated with speed (Study 1), that psychological distance is seen as compatible with slow and proximity with fast (Study 2), that stimulus psychological distance affects its perceived speed (Study 3), and that stimulus speed affects its psychological distance (Study 4). Study Set II examined the association between construal level and speed. Findings show that construal level is explicitly associated with speed (Study 5), that abstract is seen as compatible with slow and concrete with fast (Study 6), that natural language word distribution structures reflect an association between abstractness and speed (Study 7), that construal level affects speed (Study 8), and that speed affects stimulus construal level (Study 9). Study Set III examined implications for communication and person perception. Findings suggest that slow-paced (vs. fast-paced) speech is associated with larger perceived spatial and social distance between speaker and audience and larger audiences (Studies 10a, 10b) and that people infer an expansive (contractive) regulatory scope from slow-paced (fast-paced) spoken messages (Study 11). We elaborate on possible mechanisms and their theoretical and practical implications in domains including decision making and urban design. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

PyOKR: A Semi-Automated Method for Quantifying Optokinetic Reflex Tracking Ability.

The study of behavioral responses to visual stimuli is a key component of understanding visual system function. One notable response is the optokinetic reflex (OKR), a highly conserved innate behavior necessary for image stabilization on the retina. The OKR provides a robust readout of image tracking ability and has been extensively studied to understand visual system circuitry and function in animals from different genetic backgrounds. The OKR consists of two phases: a slow tracking phase as the eye follows a stimulus to the edge of the visual plane and a compensatory fast phase saccade that resets the position of the eye in the orbit. Previous methods of tracking gain quantification, although reliable, are labor intensive and can be subjective or arbitrarily derived. To obtain more rapid and reproducible quantification of eye tracking ability, we have developed a novelsemi-automated analysis program, PyOKR, that allows for quantification of two-dimensional eye tracking motion in response to any directional stimulus, in addition to being adaptable to any type of video-oculography equipment. This method provides automated filtering, selection of slow tracking phases, modeling of vertical and horizontal eye vectors, quantification of eye movement gains relative to stimulus speed, and organization of resultant data into a usable spreadsheet for statistical and graphical comparisons. This quantitative and streamlined analysis pipeline, readily accessible via PyPI import, provides a fast and direct measurement of OKR responses, thereby facilitating the study of visual behavioral responses.

Stimulus specificity in combined action observation and motor imagery of typing.

Combined action observation and motor imagery (AO + MI) can improve movement execution (ME) in healthy adults and certain patient populations. However, it is unclear how the specificity of the observation component during AO + MI influences ME. As generalised observation could result in more flexible AO + MI rehabilitation programmes, this study investigated whether observing typing of target words (specific condition) or non-matching words (general condition) during AO + MI would have different effects on keyboard typing in healthy young adults. In Experiment 1, 51 students imagined typing a target word while watching typing videos that were either specific to the target word or general. There were no differences in typing execution between AO + MI conditions, though participants typed more slowly after both AO + MI conditions compared with no observation or imagery. Experiment 2 repeated Experiment 1 in 20 students, but with a faster stimulus speed in the AO + MI conditions and increased cognitive difficulty in the control condition. The results showed that the slowed typing after AO + MI was likely due to a strong influence of task-switching between imagery and execution, as well as an automatic imitation effect. Both experiments demonstrate that general and specific AO + MI comparably affect ME. In addition, slower ME following both AO + MI and a challenging cognitive task provides support for the motor-cognitive model of MI.

Increase in speed eliminates duration expansion of a novel motion stimulus.

A novel motion stimulus is perceived to last longer than the subsequent motion stimulus moving in the opposite direction. A previous study suggested that the discrepancy in the processing latency for different onset types, as measured by reaction time, may play a role in this duration expansion. The present study examined whether the speed of motion stimuli influences this duration expansion. Experiment 1 demonstrated that the duration expansion ceased to occur when the stimulus speed increased. Experiment 2 showed that the increase in the speed reduced the reaction time for various onset types. However, the size of the changes in the reaction time did not match the reduction in the magnitude of the duration expansion observed in Experiment 1. These results suggest that the increase in speed eliminates the duration expansion of the novel motion stimulus, but the difference in the processing latency alone may not be the sole mechanism.

Cognitive deficits and enhancements in youth from adverse conditions: An integrative assessment using Drift Diffusion Modeling in the ABCD study.

Childhood adversity can lead to cognitive deficits or enhancements, depending on many factors. Though progress has been made, two challenges prevent us from integrating and better understanding these patterns. First, studies commonly use and interpret raw performance differences, such as response times, which conflate different stages of cognitive processing. Second, most studies either isolate or aggregate abilities, obscuring the degree to which individual differences reflect task-general (shared) or task-specific (unique) processes. We addressed these challenges using Drift Diffusion Modeling (DDM) and structural equation modeling (SEM). Leveraging a large, representative sample of 9-10 year-olds from the Adolescent Brain Cognitive Development (ABCD) study, we examined how two forms of adversity-material deprivation and household threat-were associated with performance on tasks measuring processing speed, inhibition, attention shifting, and mental rotation. Using DDM, we decomposed performance on each task into three distinct stages of processing: speed of information uptake, response caution, and stimulus encoding/response execution. Using SEM, we isolated task-general and task-specific variances in each processing stage and estimated their associations with the two forms of adversity. Youth with more exposure to household threat (but not material deprivation) showed slower task-general processing speed, but showed intact task-specific abilities. In addition, youth with more exposure to household threat tended to respond more cautiously in general. These findings suggest that traditional assessments might overestimate the extent to which childhood adversity reduces specific abilities. By combining DDM and SEM approaches, we can develop a more nuanced understanding of how adversity affects different aspects of youth's cognitive performance. RESEARCH HIGHLIGHT: To understand how childhood adversity shapes cognitive abilities, the field needs analytical approaches that can jointly document and explain patterns of lowered and enhanced performance. Using Drift Diffusion Modeling and Structural Equation Modeling, we analyzed associations between adversity and processing speed, inhibition, attention shifting, and mental rotation. Household threat, but not material deprivation, was mostly associated with slower task-general processing speed and more response caution. In contrast, task-specific abilities were largely intact. Researchers might overestimate the impact of childhood adversity on specific abilities and underestimate the impact on general processing speed and response caution using traditional measures.

People with dyslexia or dyscalculia are less biased: Results of a preregistered study from over 450,000 people on the implicit association test

The implicit association test (IAT) provides a sensitive measure of attitudes to social dimensions such as race, gender or disability using a response speed procedure. The automatisation deficit account of dyslexia attributes the reading (and broader) difficulties of dyslexic people to reduced speed and strength of stimulus–response habit formation and, therefore, predicts reduced implicit bias for individuals with dyslexia. This novel prediction was tested using the ‘Project Implicit’ IAT database on attitudes to disability. Data from over 460,000 respondents was analysed, including 22,747 with physical disability (PD), 14,700 with dyslexia, and 1721 with dyscalculia. The dyslexia group did indeed show significantly less ‘Disability Bias’ than both the PD and no disability groups. Intriguingly, the dyscalculia group showed significantly less disability bias even than the dyslexia group. The results are interpreted within the learning framework of broader automatisation deficit and have ramifications for understanding both conditions and the processes of development of implicit bias in neurodiverse and neurotypical populations.

Background matching can reduce responsiveness of jumping spiders to stimuli in motion.

Motion and camouflage were previously considered to be mutually exclusive, as sudden movements can be easily detected. Background matching, for instance, is a well-known, effective camouflage strategy where the colour and pattern of a stationary animal match its surrounding background. However, background matching may lose its efficacy when the animal moves, as the boundaries of the animal become more defined against its background. Recent evidence shows otherwise, as camouflaged objects can be less detectable than uncamouflaged objects even while in motion. Here, we explored whether the detectability of computer-generated stimuli varies with the speed of motion, background (matching and unmatching) and size of stimuli in six species of jumping spiders (Araneae: Salticidae). Our results showed that, in general, the responsiveness of all six salticid species tested decreased with increasing stimulus speed regardless of whether the stimuli were conspicuous or camouflaged. Importantly, salticid responses to camouflaged stimuli were significantly lower compared with those to conspicuous stimuli. There were significant differences in motion detectability across species when the stimuli were conspicuous, suggesting differences in visual acuity in closely related species of jumping spiders. Furthermore, small stimuli elicited significantly lower responses than large stimuli across species and speeds. Our results thus suggest that background matching is effective even when stimuli are in motion, reducing the detectability of moving stimuli.

Need for (expected) speed: Exploring the indirect influence of trial type consistency on representational momentum

The biases affecting people’s perception of dynamic stimuli are typically robust and strong for specific stimulus configurations. For example, representational momentum describes a systematic perceptual bias in the direction of motion for the final location of a moving stimulus. Under clearly defined stimulus configurations (e.g., specific stimulus identity, size, speed), for example, the frequently used “implied motion” trial sequence, for which a target is subsequently presented in a consistent direction and with a consistent speed, a displacement in motion direction is evidenced. The present study explores the potential influence of expectations regarding directional as well as speed consistencies on representational momentum, elicited by including other, inconsistently moving trial types within the same experimental block. A systematic representational momentum effect was observed when only consistent motion trials were presented. In contrast, when inconsistent target motion trials were mixed within the same block of experimental trials, the representational momentum effect decreased, or was even eliminated (Experiments 1 & 2). Detailed analysis indicated that this reflects a global (proportion of consistent and inconsistent motion trials within a particular experimental block), not local (preceding trial influencing actual trial) effect. Yet, additional follow-up studies (Experiments 3 & 4) support the idea that these changes in perceived location are strongly influenced by the overall stimulus speed statistics in the different experimental blocks. These results are discussed and interpreted in light of recent theoretical developments in the literature on motion perception that highlight the importance of expectations about stimulus speed for motion perception.

The Effect of Actuation Speed on the Perception Threshold of a Squeezing Soft Actuator.

The actuation speed of a pressure stimulus may influence its perception threshold. This is relevant for the design of haptic actuators and haptic interaction. We ran a study using a motorized ribbon to apply pressure stimuli (squeezes) to the arm at three different actuation speeds and used the PSI method to find the perception threshold for 21 participants. We found a significant effect of actuation speed on the perception threshold. Namely, a lower speed seems to increase the thresholds of normal force, pressure and indentation. This could be due to multiple factors like temporal summation, stimulating a larger population of mechanoreceptors for faster stimuli, and different responses of SA and RA receptors to stimuli of varying speeds. Our results show that actuation speed is an important parameter for the design of new haptic actuators and the design of haptic interaction for pressure.

A metacognitive approach to the study of motion-induced duration biases reveals inter-individual differences in forming confidence judgments.

Our ability to estimate the duration of subsecond visual events is prone to distortions, which depend on both sensory and decisional factors. To disambiguate between these two influences, we can look at the alignment between discrimination estimates of duration at the point of subjective equality and confidence estimates when the confidence about decisions is minimal, because observers should be maximally uncertain when two stimuli are perceptually the same. Here, we used this approach to investigate the relationship between the speed of a visual stimulus and its perceived duration. Participants were required to compare two intervals, report which had the longer duration, and then rate their confidence in that judgment. One of the intervals contained a stimulus drifting at a constant speed, whereas the stimulus embedded in the other interval could be stationary, linearly accelerating or decelerating, or drifting at the same speed. Discrimination estimates revealed duration compression for the stationary stimuli and, to a lesser degree, for the accelerating and decelerating stimuli. Confidence showed a similar pattern, but, overall, the confidence estimates were shifted more toward higher durations, pointing to a small contribution of decisional processes. A simple observer model, which assumes that both judgments are based on the same sensory information, captured well inter-individual differences in the criterion used to form a confidence judgment.

The effect of real-world and retinal motion on speed perception for motion in depth.

For motion in depth, even if the target moves at a constant speed in the real-world (physically), it would appear to be moving with acceleration on the retina. Therefore, the purpose of this study was to determine whether real-world and retinal motion affect speed perception in depth and to verify the influence of eye movements on both motion signals in judging speed in depth. We used a two-alternative forced-choice paradigm with two types of tasks. One stimulus moved at a constant speed in the real-world (world constant task) with three conditions: 80-60 cm (far), 60-40 cm (middle), and 40-20 cm (near) from the participant. The other stimulus moved at a constant speed on the retina (retinal constant task) with three conditions: 4-8 deg (far), 8-12 deg (middle), and 12-16 deg (near) as the vergence angle. The results showed that stimulus speed was perceived faster in the near condition than in the middle and far conditions for the world constant task, regardless of whether it was during fixation or convergence eye movements. In contrast, stimulus speed was perceived faster in the order of the far, middle, and near conditions for the retinal constant task. Our results indicate that speed perception of a visual target approaching the observer depends on real-world motion when the target position is relatively far from the observer. In contrast, retinal motion may influence speed perception when the target position is close to the observer. Our results also indicate that the effects of real-world and retinal motion on speed perception for motion in depth are similar with or without convergence eye movements. Therefore, it is suggested that when the visual target moves from far to near, the effects of real-world and retinal motion on speed perception are different depending on the initial target position.

Effects of speed, motion type, and stimulus size on dynamic visual search: A study of radar human–machine interface

Human visual perception behavior in dynamic environments could be affected by the motion properties of stimuli. The purpose of this study was to investigate the effects of motion type, size, and speed of stimulus on visual search performance and visual comfort in both single- and double-target tasks. Twenty participants attended an experiment in which they finished two tasks at three speeds (low, medium, and high), in two motion types (flicker, uniform), with varied levels of stimulus size (small, medium, and large) on a display. The search time, accuracy, critical flicker frequency, visual comfort, and cognitive load were recorded to provide a comprehensive understanding of participants' visual preferences during the experiment.The results indicated the increasing speed would weaken participants performance on visual search tasks; Medium-sized stimuli were recommended considering search efficiency and cost-effectiveness; More importantly, the present study also found that flicker motion led to better task performance in the low-speed task, due to increased alertness and lead physiological arousal effects, which may imply the past studies have overstated the negative effects of flickering in dynamic environments.

Are head-down tilt bedrest studies capturing the true nature of spaceflight-induced cognitive changes? A review.

Although a number of studies have examined cognitive functions in space, the reasons behind the observed changes described by space research and anecdotal reports have not yet been elucidated. A potential source of cognitive changes is the cephalad fluid shift in the body caused by the lack of hydrostatic pressure under microgravity. These alterations can be modeled under terrestrial conditions using ground-based studies, such as head-down tilt bedrest (HDBR). In this review, we compare the results of the space and HDBR cognitive research. Results for baseline and in-flight/in-HDBR comparisons, and for baseline and post-flight/post-HDBR comparisons are detailed regarding sensorimotor skills, time estimation, attention, psychomotor speed, memory, executive functions, reasoning, mathematical processing, and cognitive processing of emotional stimuli. Beyond behavioral performance, results regarding brain electrical activity during simulated and real microgravity environments are also discussed. Finally, we highlight the research gaps and suggest future directions.

Memristive Circuit Design of Nonassociative Learning under Different Emotional Stimuli

Most memristor-based circuits only consider the mechanism of nonassociative learning, and the effect of emotion on nonassociative learning is ignored. In this paper, a memristive circuit that can realize nonassociative learning under different emotional stimuli is designed. The designed circuit consists of stimulus judgment module, habituation module, sensitization module, emotion module. When different stimuli are applied, habituation or sensitisation is formed based on the intensity and nature of the stimuli. In addition, the influence of emotion on nonassociative is considered. Different emotional stimuli will affect the speed of habituation formation and strong negative stimuli will lead to sensitization. The simulation results on PSPICE show that the circuit can simulate the above complex biological mechanism. The memristive circuit of nonassociative learning under different emotional stimuli provides some references for brain-like systems.

Effects of Sitting Callisthenic Balance and Resistance Exercise Programs on Cognitive Function in Older Participants.

Exercise training programs have the potential to improve cognitive function in older subjects. However, the majority of training programs are based on aerobic modality. In the current study, the influence of 3 months programs of sitting callisthenic balance (SCB) and resistance training (RT) on cognitive functioning and the mediating role that a change in the level of neurotrophic factors and strength in older, healthy participants plays were examined. Global cognitive function was examined using MoCA, short-term memory using Digit Span and Delayed Matching to Sample, set shifting using Trial Making Test Part B, speed of processing simple visual stimuli using Simple Reaction Time, decision making using Choice Reaction Time, visual attention with Visual Attention Test (VAT), tests. Strength of lower and upper limbs, neurotrophin level (irisin, brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT-3), neurotrophin 4/5 (NT 4/5) were examined. Improved scores in RT vs. SCB were noted in MoCA (p = 0.02), reaction time in SRT (p = 0.02), TMT B (p = 0.03), errors committed in CRT (p = 0.04) and VAT (p = 0.02) were observed. No significant changes in the level of neurotrophic factors were observed. Changes in upper limb strength were related to changes in the number of errors committed in the SRT (p = 0.03). Lower limb strength changes explained the dynamics of the number of correct answers (p = 0.002) and errors committed (p = 0.006) in VAT. Both SCB and RT influenced multiple cognitive domains. The RT program improved global cognitive functioning, while no improvement was noticed in the SCB group. Decision making, visual attention and global cognitive function were improved after the RT program. Set-shifting, short-term visual memory processing speed of simple visual stimuli were improved after the SCB program, while a decrease in the processing speed of simple visual stimuli was noted in the RT group. Changes in irisin were related to set-shifting and short-term memory, while in BDNF to an improvement in the processing speed of simple visual stimuli. Resistance exercise training programs could be applied to prevent age related declines of cognitive function in healthy older subjects.

The speed prior account: A new theory to explain multiple phenomena regarding dynamic information.

Our perception of moving stimuli is prone to systematic biases. Different biases, for example concerning the perceived speed, or spatial location, of a dynamic, moving stimulus, have consistently been reported in the literature. Different lines of experimental research, together with different theoretical explanations, have emerged analyzing and discussing these biases separately. In the present study, we propose a new theoretical account to unite various effects relating to dynamic/moving stimuli: The speed prior account. The perceived location of a stimulus is suggested to reflect the combination of the sensory input, which is associated with uncertainty, and a prior expectation concerning stimulus speed. Discrepancies between the prior speed expectation and the actual speed of a stimulus then result in a distortion of perceived stimulus speed, leading to the various perceptual biases that have been observed. In the present study, we demonstrate that this new theory can already account for robust data patterns currently unexplained in the literature, while we additionally directly test the predictions of the new speed prior account across four experiments. The influence of stimulus speed was manipulated in two visual as well as two tactile studies (all N = 30). The results reveal a clear data pattern, consistent with the speed prior account, as perceived onset and offset location reveal strong interdependencies. The implications and possible future questions for the perception of moving stimuli, in particular, and dynamic information, more generally, are discussed. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

A normative model of peripersonal space encoding as performing impact prediction

Accurately predicting contact between our bodies and environmental objects is paramount to our evolutionary survival. It has been hypothesized that multisensory neurons responding both to touch on the body, and to auditory or visual stimuli occurring near them—thus delineating our peripersonal space (PPS)—may be a critical player in this computation. However, we lack a normative account (i.e., a model specifying how we ought to compute) linking impact prediction and PPS encoding. Here, we leverage Bayesian Decision Theory to develop such a model and show that it recapitulates many of the characteristics of PPS. Namely, a normative model of impact prediction (i) delineates a graded boundary between near and far space, (ii) demonstrates an enlargement of PPS as the speed of incoming stimuli increases, (iii) shows stronger contact prediction for looming than receding stimuli—but critically is still present for receding stimuli when observation uncertainty is non-zero—, (iv) scales with the value we attribute to environmental objects, and finally (v) can account for the differing sizes of PPS for different body parts. Together, these modeling results support the conjecture that PPS reflects the computation of impact prediction, and make a number of testable predictions for future empirical studies.