David Rose

The Perception of Emotion from Body Movement in Point-Light Displays of Interpersonal Dialogue

We examined whether it is possible to identify the emotional content of behaviour from point-light displays where pairs of actors are engaged in interpersonal communication. These actors displayed a series of emotions, which included sadness, anger, joy, disgust, fear, and romantic love. In experiment 1, subjects viewed brief clips of these point-light displays presented the right way up and upside down. In experiment 2, the importance of the interaction between the two figures in the recognition of emotion was examined. Subjects were shown upright versions of (i) the original pairs (dyads), (ii) a single actor (monad), and (iii) a dyad comprising a single actor and his/her mirror image (reflected dyad). In each experiment, the subjects rated the emotional content of the displays by moving a slider along a horizontal scale. All of the emotions received a rating for every clip. In experiment 1, when the displays were upright, the correct emotions were identified in each case except disgust; but, when the displays were inverted, performance was significantly diminished for some emotions. In experiment 2, the recognition of love and joy was impaired by the absence of the acting partner, and the recognition of sadness, joy, and fear was impaired in the non-veridical (mirror image) displays. These findings both support and extend previous research by showing that biological motion is sufficient for the perception of emotion, although inversion affects performance. Moreover, emotion perception from biological motion can be affected by the veridical or non-veridical social context within the displays.

Perceptual learning of luminance contrast detection: specific for spatial frequency and retinal location but not orientation

Performance of a wide range of simple visual tasks improves with practice. Here we ask whether such learning occurs for the fundamental visual task of luminance contrast detection. In two experiments we find that contrast sensitivity increases following extensive practice at detecting briefly presented sinusoidal luminance gratings and that learning is maintained after six months. Learning is spatial frequency tuned, specific to retinal location and can be specific to one eye, but is not selective for orientation. The selectivity of learning implies that it is based on plasticity in early visual, as opposed to central cognitive, processing mechanisms.

DURATION ILLUSIONS IN A TRAIN OF VISUAL STIMULI

The first stimulus in a sequential train of identical flashes of light appears to last longer than those in the middle of the train. Four flashes (each 600 or 667 ms) were presented and the first was shortened until it appeared to have the same duration as that of the next. The duration of the first stimulus was found to be overestimated by about 50%. The illusion was unaffected by stimulus contrast, size, or interflash interval (between 100 and 600 ms). For some subjects, the last stimulus in the train also appeared to be about 50% longer than the penultimate flash. The results are discussed in terms of theories of how attention, arousal, and stimulus processing can affect duration perception. The mechanisms activated are peculiar to the visual system, since no similar illusion of duration was consistently experienced with a train of auditory tones.

Prediction of Childhood Intelligence from Habituation in Early Infancy.

Abstract The present study investigated whether measures of habituation and dishabituation in early infancy predicted later ( age 4 1 2 years ) intelligence. An infant-controlled habituation procedure was used and each infant was tested on three separate occasions. Statistically reliable correlations between the two ages were obtained, and these were specific to: (a) verbal components of the child intelligence test scores; (b) measures derived from the familiarization of habituation phase of the infant testing, rather than from subsequent dishabituation or novelty response scores. The predictive infant measures were only those which minimally satisfied both of two psychometric criteria: (1) There are consistent changes with age; (2) there is test-retest reliability, with age partialled out. The results are compared with those from other comparable studies, and it is argued that the psychometric acceptability of infant cognitive measures needs to be demonstrated before they can be considered to be potential predictors.

Habituation in the newborn

Four experiments are described in which the newborns ability to habituate to a visual stimulus and subsequently to display novelty/familiarity preferences was explored. The same two types of stimuli, simple geometric shapes and complex colored patterns, were used throughout. The results suggest that newborns will reliably give novelty preferences when an infant-controlled habituation procedure is used. However, no reliable preferences emerged following either a brief exposure to a stimulus, or when novel and familiar stimuli were presented paired together over several trials. In experiment 4 different, novel stimuli were presented on successive infant-controlled trials and the decline in trial length observed during habituation trials was not found. Although this is further evidence that habituation to a repeated visual stimulus does occur in the newborn, half of the subjects in experiment 4 would have met the infant-controlled criterion of habituation: these results are discussed in terms of artifacts that can affect habituation. While there is considerable intra-and intersubject variability in trial duration, and in other dependent measures, the results give support to the model of habituation which assumes it to be an exponentially decreasing process.

Mechanisms underlying the receptive field properties of neurons in cat visual cortex

Abstract Several previous models of the circuitry of the cats primary visual cortex are briefly described and various difficulties with them are pointed out. It is argued that the situation is more complicated than any of these models supposed, and that some of the anomalies in previous models can be overcome if additional factors are considered. A new model is proposed in which cells with strong hypercomplex properties are driven directly by geniculate cells with superimposed receptive fields, and other cortical cells are driven by geniculate cells with more scattered receptive fields. This model accounts for many of the response properties of cortical cells.

On the Variety of Percepts Associated with Dichoptic Viewing of Dissimilar Monocular Stimuli

Upon dichoptic viewing of dissimilar patterns, several distinct perceptual states may be experienced over time. One state is exclusive monocular dominance, wherein the view of only one eye is seen in its entirety for some period of time. Another state is characterized by a mosaic-like collage consisting of portions of the view of each eye. Two other states involve simultaneous perception of both monocular images in their entirety. In one of these states, the two monocular stimuli appear to be superimposed without depth (a phenomenon we shall term ‘superimposition’). In the other state, the two monocular stimuli appear to be located at different depth planes (which we shall term ‘transparency’). This paper documents the stimulus conditions favoring these various perceptual states. Exclusive monocular dominance occurs most often when the two eyes view dissimilar patterns with the same spatial-frequency content, particularly when both patterns consist of low spatial frequencies. Superimposition also occurs most often when the two eyes view the same spatial frequencies, but predominantly when those spatial frequencies are high. Transparency is favored when the spatial-frequency difference between the eyes is great, particularly when the view of one eye consists of high spatial-frequency information.

Dynamics of Adaptation to Contrast

An investigation has been made into the temporal parameters with which the detection threshold for a sinusoidal grating changes during and after adaptation to the same grating at high contrast. Stationary high-spatial-frequency gratings and a phase-reversing low-spatial-frequency grating have been studied separately. It was found that the threshold continues to rise during adaptation for at least 6 min without sign of levelling off, and that full recovery from 6 min of adaptation can take more than 45 min. Intermittent adaptation and continuous adaptation for the same period produce similar effects. Single-phase and dual-phase exponential fits to the data are rejected, and it is concluded that the level of adaptation of the visual system to spatial contrast changes as a power function of time. However, recovery is not always monotonic, especially after adaptation to phase-reversing gratings. This may be due to inhibitory interactions between channels (in particular, those for pattern and movement information).

Interocular Transfer of Expansion, Rotation, and Translation Motion Aftereffects

The motion aftereffect demonstrates the existence of direction-selective mechanisms in the visual system. However, direction-selective cells exist within many visual areas, including V1 and MT/V5. Can motion aftereffects be generated within each of these areas? In visual cortical areas beyond V1 almost all cells are binocular, whereas a smaller percentage are binocular in V1. The degree of binocularity can be revealed psychophysically by assessing interocular transfer. Interocular transfer of motion aftereffects generated from expanding, rotating, and translating dynamic random-dot patterns were therefore compared, since these stimuli should activate cells in higher visual areas selectively. Partial interocular transfer was found that was greater for expansion and rotation than for translation. The results support the involvement of higher visual areas in motion aftereffects to complex animation sequences.

Locus of habituation in the human newborn.

There is some controversy concerning the youngest age at which an infant will habituate to a visual stimulus or will prefer a novel to a familiar pattern. One suggestion has been that apparently successful reports of habituation and dishabituation in the newborn baby are attributable to retinal adaptation. This interpretation was tested in two experiments. In both experiments monocular conditions of viewing were used: newborns were habituated with one eye as the ‘seeing’ eye, and posthabituation novelty preferences investigated with the other eye. Significant preferences were found both for a novel colour (experiment 1) and for a novel shape (experiment 2), which implies that a retinal-adaptation model can be ruled out. It is suggested that the habituation effects and the subsequent novelty preferences found in the experiments are most reasonably interpreted as a function of memory formation, and evidence is presented for the storage of visual experience from birth. The results also demonstrate some form of binocular interaction in the newborn.