Temporal covariance model of human motion perception

Abstract

We propose a model of direction-sensitive units in human vision. It is a modified and elaborated version of a model by Reichardt [Z. Naturforsch. Teil B 12, 447 (1957)]. The model is applied to threshold experiments in which subjects view adjacent vertical bars with independently (typically sinusoidally), temporally modulated luminances.The subject must report whether the patterns moved to the left or to the right. According to the model, a basic motion-detecting unit consists of two subunits tuned to opposite directions. Each performs a spatial and temporal linear filtering of its input; outputs of the filters are multiplied, and the multiplied output is integrated (for a time that is long relative to the modulation period). The model's output consists of the difference between the subunit outputs. Direction of movement is indicated by the sign of the model output. Mathematical analysis of the model yielded several predictions that were confirmed experimentally.Specifically, we found that (1) performance with complex patterns can be predicted by spatiotemporal Fourier analysis that results in the segregation and linear addition in the output for different temporal frequencies; (2) under special conditions, performance depends on the product of adjacent bar amplitudes, offering strong support for the multiplication principle; (3) performance is unaffected by addition of stationary patterns; and (4) addition of homogeneous flicker normally produces no effect but under special conditions reverses perceived direction. These and other results confirm our model and reject several other models, including Reichardt's original model.

Full-wave and half-wave rectification in second-order motion perception

“…Adelson & Bergen, 1985;van Santen & Sperling, 1984;Watson & Ahumada, 1985), a single mechanism cannot simultaneously signal opposite directions-motion in opposite directions is perceived as counterphase flicker. Therefore we conclude that, on a significant portion of trials, JS demonstrates an ability to access two different mechanisms for processing full-wave and half-wave stimuli.…”

The complementary brain: unifying brain dynamics and modularity

“…These are large questions with complex answers on which many investigators are working. Classical computational models of motion detection involving Reichardt-like or motion-energy mechanisms have focused on the recovery of local motion directions [33][34][35] . Cells in motion processing areas like MT, however, are sensitive to both the direction and the speed of moving patterns 20,36 .…”

Visualizing retinotopic half-wave rectified input to the motion detection circuitry of Drosophila

“…Notably, the HRM precisely describes in algorithmic terms the observed optomotor behaviour of walking beetles and walking and flying flies 12,13 . Furthermore, the fundamental computations of the HRM can explain motion detection in different vertebrate species including man [14][15][16][17] . In flies, directionally selective responses that closely match the predictions of the model were observed in the large tangential neurons of both (reviewed in 18 ) large fly species (reviewed in 5 ) and Drosophila 19,20 .…”