It may be simpler to consider well-being to be a unidimensional construct, as hypothesized, for example, by the Oxford Happiness Questionnaire (Hills & Argyle, 2002) or by the single-item measures proposed in several contexts (

Perceived surface orientation and angular velocity were investigated for orthographic projections of 3-D rotating random-dot planes. It was found that (a) tilt was accurately perceived and (b) slant and angular velocity were systematically misperceived. It was hypothesized that these misperceptions are the product of a heuristic analysis based on the deformation, one of the differential invariants of the first-order optic flow. According to this heuristic, surface attitude and angular velocity are recovered by determining the magnitudes of these parameters that most likely produce the deformation of the velocity field, under the assumption that all slant and angular velocity magnitudes have the same a priori probability. The results of the present investigation support this hypothesis. Residual orientation anisotropies not accounted for by the proposed heuristic were also found.

Many visual tasks are carried out by using multiple sources of sensory information to estimate environmental properties. In this paper, we present a model for how the visual system combines disparity and velocity information. We propose that, in a first stage of processing, the best possible estimate of the affine structure is obtained by computing a composite score from the disparity and velocity signals. In a second stage, a maximum likelihood Euclidean interpretation is assigned to the recovered affine structure. In two experiments, we show that human performance is consistent with the predictions of our model. The present results are also discussed in the framework of another theoretical approach of the depth cue combination process termed Modified Weak Fusion.

No abstract

Perceived depth in the stereokinetic effect (SKE) illusion and in the monocular derivation of depth from motion parallax were compared. Motion parallax gradients of velocity can be decomposed into 2 components: object-and observer-relative transformations. SKE displays present only the object-relative component. Observers were asked to estimate the magnitude and near-far order of depth in motion parallax and SKE displays. Monocular derivation of depth magnitude from motion parallax is fully accounted for by the perceptual response to the SKE, and observerrelative transformations absent in the SKE are of perceptual utility only as determinants of the near-far signing of perceived sequential depth. The amount of depth and rigidity perceived in motion parallax and SKE displays covaries with the projective size of the stimuli. The monocular derivation of depth from motion is mediated by a perceptual heuristic of which the SKE is symptomatic.The perception of depth from monocular motion information occurs in three situations, two yielding veridical depth percepts and the third giving rise to an illusion. First, depth is perceived when one views an object that is rotating around some axis other than the line of sight. Second, depth is seen when a viewer moves past stationary objects, or conversely when objects translate by a stationary observer on some path other than the line of sight. The depth-evoking optical transformations that occur in these situations are called motion parallax. Finally, depth is observed when one views certain two-dimensional patterns that are rotating in the picture plane. Called the stereokinetic effect (SKE) by Musatti (1924), these phenomena are illusory because here the distal objects are, in fact, two-dimensional.In this article, we propose that the SKE illusion is symptomatic of the processes by which the visual system derives depth in everyday situations. Proffitt, Rock, H. Hecht, and Schubert (1992) decomposed rigid object rotations into two motion transformations, one of which defines the stimulus basis for the SKE. They showed that the perceptual response to the SKE is indicative of how people perceive depth when they observe small object rotations of 15° or less. Through a similar analysis, we show here that motion parallax can be decomposed into two transformations, one of which again defines the stimulus basis for the SKE. In four experiments, we show that when they perceive depth magnitude in motion parallax displays, people use only that motion component that exists in SKE displays. The remaining motion transformation has perceptual utility only for the specification of depth order or the near-far signing of perceived sequential depth. Finally, we show that because depth mag-