10 pags., 5 figs., 8 tabs., Recent results have shown that males have lower duration thresholds for motion direction discrimination than females. Measuring contrast thresholds, a previous study has shown that males have a greater sensitivity to fine details and fast flickering stimuli than females, and that females have a higher sensitivity to low spatial frequencies modulated at low temporal frequencies. Here, we present the data of a contrast-detection motion discrimination experiment and a reanalysis of four different motion discrimination experiments where we compare duration thresholds for males and females using different spatial frequencies, stimulus sizes, contrasts, and temporal frequencies (in two experiments, motion surround suppression was measured). Results from the main experiment and the reanalysis show that, in general, the association between sex and contrast and duration thresholds for motion discrimination is not significant, with males and females showing similar data patterns. Only the reanalysis of one out of four studies revealed different duration thresholds between males and females paired with a strong effect size supporting previous results in the literature, although motion surround suppression was identical between groups. Importantly, most of our results do not show significant differences between males and females in contrast and duration thresholds, suggesting that the sex variable may not be as relevant as previously claimed when testing visual motion discrimination., Supported by grant PID2021-122245NB-I00 from Ministerio de Ciencia e Innovación (Spain) to ISP. The funding source was not involved in the preparation of this article. RL is supported by a Juan de la Cierva-Formación fellowship (FJC2020-044084-I) funded by MCIN/AEI /10.13039/501100011033 and by the European Union Next Generation EU/PRTR., Peer reviewed

11 pages, 8 figures, The estimation of motion is an essential process for any sighted animal. Computational models of motion sensors have a long and successful history but they still suffer from basic shortcomings, as they disagree with physiological evidence and each model is dedicated to a specific type of motion, which is controversial from a biological standpoint. In this work, we propose a new approach to modeling motion sensors that considers dendritic computations, a key aspect for predicting single-neuron responses that had previously been absent from motion models. We show how, by taking into account the dynamic and input-dependent nature of dendritic nonlinearities, our motion sensor model is able to overcome the fundamental limitations of standard approaches., Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. R.L. was supported by a Juan de la Cierva-Formación fellowship (FJC2020-044084-I) funded by Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación (Spain) and by the European Union NextGenerationEU/PRTR. I.S-P was supported by grant PID2021-122245NB-I00, from Ministerio de Ciencia e Innovación (Spain). M.B. was supported by project VIS4NN, Programa Fundamentos 2022, Fundación BBVA, and by grant PID2021-127373NB-I00, Ministerio de Ciencia e Innovación (Spain)., Peer reviewed

Masking experiments, using vertical and horizontal sinusoidal depth corrugations,
have suggested the existence of more than two spatial-frequency disparity
mechanisms. This result was confirmed through an individual differences
approach. Here, using factor analytic techniques, we want to investigate the
existence of independent temporal mechanisms in frontoparallel stereoscopic
(cyclopean) motion. To construct stereomotion, we used sinusoidal depth
corrugations obtained with dynamic random-dot stereograms. Thus, no luminance
motion was present monocularly. We measured disparity thresholds for
drifting vertical (up-down) and horizontal (left-right) sinusoidal corrugations
of 0.4 cyc/deg at 0.25, 0.5, 1, 2, 4, 6, and 8 Hz. In total, we tested 34 participants.
Results showed a small orientation anisotropy with lower thresholds for horizontal
corrugations. Disparity thresholds as a function of temporal frequency
were almost constant from 0.25 up to 1 Hz, and then they increased monotonically.
Principal component analysis uncovered two significant factors for
vertical and two for horizontal corrugations. Varimax rotation showed that
one factor loaded from 0.25 to 1–2 Hz and a second factor from 2 to 4 to 8 Hz.
Direct Oblimin rotation indicated a moderate intercorrelation of both factors.
Our results suggest the possible existence of two somewhat interdependent
temporal mechanisms involved in frontoparallel stereomotion.

Data set from paper: The stereoscopic anisotropy is smaller in elderly population

Purpose: There is a well-known orientation anisotropy in stereovision, where disparity thresholds for sinusoidal corrugations of low spatial frequencies are much higher for vertical than for horizontal orientations. While previous research has indicated that the visual system responds more rapidly to horizontal than vertical slanted surfaces, the spatiotemporal characteristics underlying the stereoscopic anisotropy have not been thoroughly studied. This study aims to quantify the anisotropy across a range of spatial and temporal frequencies.

Methods: We measured disparity thresholds for vertical and horizontal sinusoidal corrugations across different spatial (from 0.05 to 0.8 cpd) and temporal frequencies (from 0 to 8 Hz). To interpret the data, we fitted a spatiotemporal cross-correlation model (that approximates the disparity-energy calculation in V1). The model included a shift parameter to capture the differences in sensitivity between orientations.

Results: Disparity thresholds as a function of temporal frequency revealed a low-pass shape. Across all conditions, thresholds were consistently higher for vertical than for horizontal corrugations. The degree of anisotropy decreased with increasing spatial frequency and was strongest at lower spatial frequencies. Model fits revealed similar spatial and temporal weighting functions for both orientations, with a global vertical shift accounting for the reduced sensitivity observed for vertical corrugations.

Conclusions: This study provides a systematic characterization of the spatiotemporal properties of stereoscopic anisotropy. Disparity thresholds were consistently higher for vertical than for horizontal corrugations, particularly at low spatial frequencies and for all temporal frequencies. Our simulation results indicate that the anisotropy can be captured by a global vertical shift in sensitivity, while the spatiotemporal disparity processing is similar for both orientations.

Purpose. The stereoscopic anisotropy is one of the most intriguing phenomena of stereoscopic vision. It shows that the disparity thresholds to detect three-dimensional sinusoidal horizontal corrugations are much lower than for vertical corrugations for spatial frequencies lower than 1 cycles/deg. A recent study has shown that the anisotropy increases during childhood and that visual experience probably plays an important role in its development (Serrano-Pedraza et al., 2016). Here we want to determine the impact that the visual experience has throughout life in the stereoscopic anisotropy. Methods. We performed two experiments testing two age groups of 35 participants each: the young group aged 18 to 45 years and the old group aged 62 to 90 years. We measured disparity thresholds for three-dimensional sinusoidal corrugations of 0.1 cyc/deg, with either vertical or horizontal orientation. Detection thresholds were obtained using Bayesian adaptive staircases. For each participant we computed the anisotropy index by subtracting the thresholds in logarithmic units of the vertical minus the horizontal corrugation. Results. The analyses show that stereo thresholds for vertical corrugations are similar for both groups, however, for horizontal corrugations the thresholds are much lower for the young group. Therefore, the anisotropy was much stronger in the young group (mean, 0.67 ± 0.46) than for the old group (mean, 0.24 ± 0.3). Pearson correlation between the anisotropy index and age shows a negative and significant correlation (r = -0.49; P = 1.83 × 10-5; N = 70), that is, as age advances, the anisotropy decreases. Conclusions. Thus, visual experience plays an important role in the development of stereo vision. Although disparity thresholds for horizontal corrugations in the older group are higher, surprisingly, disparity thresholds for vertical corrugations remain stable and do not change. Therefore, the stereoscopic anisotropy decreases with aging.

Eye movements generate a perceptual challenge, that of distinguishing self-induced sensations from movement in the world. We ask about the mechanisms involved in suppressing eye movements towards self-induced sensation, ensuring visual stability. When tracking with the eyes an object moving against a textured background, the background retinal image moves in the opposite direction to the smooth pursuit eye movement. Optokinetic responses, such as optokinetic nystagmus or ocular tracking to this reafferent signal, must be suppressed to sustain the pursuit of the object of interest. We varied the contrast of a brief background motion signal to tell apart two plausible accounts of the suppression of optokinesis during pursuit; a visuomotor gain modulation account, which predicts that ocular tracking of background motion is suppressed in the same proportion irrespective of contrast, and a sensory attenuation account, which predicts that larger contrasts are needed to elicit the same response. Unexpectedly, neither account fit ocular tracking in the reafferent signal direction. The combination of contrast-dependent gating, with maximal suppression observed with higher contrasts, and either contrast gain or visuomotor gain modulation, provides a good fit for most observers’ data. Contrast-dependent gating promotes visuomotor stability in response to most salient signals, as a likely adaptation to the statistics of the environment.