Preference for biological motion in domestic chicks: sex-dependent effect of early visual experience

To examine the effects of early visual experience on preference for biological motion (BM), newly hatched chicks were exposed to a point-light animation (a visual stimulus composed of identical light points) depicting the following features of a hen: a walking hen (a BM stimulus), a rotating hen (a non-BM stimulus), a pendulum stimulus, a random motion stimulus and a stationary pattern. Chicks were then tested in a binary choice task, choosing between walking-hen and rotating-hen stimuli. Males exhibited a preference for BM if they had been trained with any animation except the stationary pattern stimulus, suggesting that the BM preference was not learned, but induced by motion stimuli. We found a significant positive correlation between the number of approaches in training and the preference in the test, but locomotion alone did not cause preference for BM. In contrast, females exhibited a particularly strong preference for walking-hen stimuli, but only when they had been trained with it. Furthermore, females (but not males) trained with random motion showed a preference for walking hen over walking cat (a biological motion animation depicting a cat), possibly suggesting that females are choosier than males. Chicks trained with a stationary pattern and untrained controls did not show a significant preference. The induction of BM preference is discussed in terms of possible ecological background of the sex differences.     

Perception of the stereokinetic illusion by the common marmoset (<Emphasis Type="Italic">Callithrix jacchus</Emphasis>)

Stereokinetic illusions have never been investigated in non-human primates, nor in other mammalian species. These illusions consist in the perception of a 3D solid object when certain 2D stimuli are rotated slowly in the plane perpendicular to the line of sight. The ability to perceive the stereokinetic illusion was investigated in the common marmoset (Callithrix jacchus). Four adult marmosets were trained to discriminate between a solid cylinder and a solid cone for food reward. Once learning criterion was reached, the marmosets were tested in sets of eight probe trials in which the two solid objects used at training were replaced by two rotating 2D stimuli. Only one of these stimuli produced, at least to the human observer, the stereokinetic illusion corresponding to the solid object previously reinforced. At test, the general behaviour and the total time spent by the marmosets observing each stimulus were recorded. The subjects stayed longer near the stimulus producing the stereokinetic illusion corresponding to the solid object reinforced at training than they did near the illusion corresponding to the previously non-rewarded stimulus. Hence, the common marmosets behaved as if they could perceive stereokinetic illusions.     

Processing of biological motion point-light displays by baboons (Papio papio)

Humans apply complex conceptual judgments to point-light displays (PLDs) representing biological motion (BM), but how animals process this kind of display remains uncertain. Four baboons (Papio papio) were trained to discriminate BM from nonbiological motion PLDs using an operant computerized test system. Transfer tests were given after training with novel BM stimuli representing humans or baboons (Experiment 1), with inverted PLDs (Experiment 2), and with BM stimuli in which body parts had been spatially disorganized (Experiment 3). Very limited transfer was obtained with the novel and inverted displays in Experiments 1 and 2, but transfer was much higher after spatial disorganization in Experiment 3. It is suggested that the baboons did not retrieve and interpret the articulated shape of the human or monkey body from the BM PLD stimuli, but rather focused their attention on the configural properties of subparts of the stimuli. Limits in perceptual grouping and restricted abilities in picture-object equivalence might explain why the baboons did not map BM PLD displays onto what they represent.     

The effects of intradimensional and extradimensional shifts on visual discrimination learning in humans and non-human primates

Human subjects and non-human primates (the common marmoset) were trained on a series of reversals of both a simple (stimuli varying along one dimension) and compound (stimuli varying along two different dimensions) visual discrimination, using computer-generated stimuli. They were then shifted to a third series of reversals using completely novel compound stimuli. Those humans and marmosets for which the previously relevant dimension remained relevant, following the shift (shapes to shapes or lines to lines; intradimensional shift) made fewer errors than those for which the previously irrelevant dimension became relevant (shapes to lines or lines to shapes; extradimensional shift). These findings suggest that both humans and marmosets can learn to attend to the specific attributes or dimensions of a stimulus and use this information in visual discrimination learning.     

Apparent reversals of a rotating mask: A new demonstration of cognition in perception

A mask of a face rotated about its vertical axis of symmetry can appear to oscillate rather than rotate. Do stimulus features (e.g., shape) or cognitive factors (e.g., differential familiarity with convex and concave views of faces) explain this new illusion? In Experiment 1, differential familiarity was varied across stimuli by using familiar and unfamiliar objects rotating at 4 rpm and within stimuli by showing the objects upright and inverted. True motion was seen more with unfamiliar objects than with familiar objects and more with an inverted mask than with an upright mask. The results of Experiment 2, which was done with static views, suggest that the upright and inverted masks present similar structure to the visual system. In Experiment 3, the objects were shown rotating at 8 rpm; the results are similar to those of Experiment 1. These experiments favor a differential familiarity account of this illusory motion. Cognitive constraints on perceived motion and perceived rigidity are discussed.     

Apparent reversals of a rotating mask: a new demonstration of cognition in perception.

A mask of a face rotated about its vertical axis of symmetry can appear to oscillate rather than rotate. Do stimulus features (e.g., shape) or cognitive factors (e.g., differential familiarity with convex and concave views of faces) explain this new illusion? In Experiment 1, differential familiarity was varied across stimuli by using familiar and unfamiliar objects rotating at 4 rpm and within stimuli by showing the objects upright and inverted. True motion was seen more with unfamiliar objects than with familiar objects and more with an inverted mask than with an upright mask. The results of Experiment 2, which was done with static views, suggest that the upright and inverted masks present similar structure to the visual system. In Experiment 3, the objects were shown rotating at 8 rpm; the results are similar to those of Experiment 1. These experiments favor a differential familiarity account of this illusory motion. Cognitive constraints on perceived motion and perceived rigidity are discussed.     

Pictures of you: Dot stimuli cause motor contagion in presence of a still human form

In this study, we investigate which visual cues induce participants to encode a non-human motion stimulus in their motor system. Participants performed reach-to-grasp actions to a target after observing a dot moving in a direct or higher-arcing path across a screen. Dot motion occurred in the presence of a meaningless (scrambled human model) stimulus, a still human model, or a human model performing a direct or exaggeratedly curved reach to a target. Our results show that observing the dot displacement causes motor contagion (changes in the height of the observer’s hand trajectory) when a human form was visually present in the background (either moving or still). No contagion was evident, however, when this human context was absent (i.e., human image scrambled and not identifiable). This indicates that visual cues suggestive of human agency can determine whether or not moving stimuli are encoded in the motor system.     

Prior knowledge about display inversion in biological motion perception

Display inversion severely impedes veridical perception of point-light biological motion (Pavlova and Sokolov, 2000 Perception & Psychophysics 62 889-899; Sumi, 1984 Perception 13 283-286). Here, by using a spontaneous-recognition paradigm, we ask whether prior information about display orientation improves biological motion perception. Participants were shown a set of 180 degrees inverted point-light stimuli depicting a human walker and quadrupeds (dogs). In experiment 1, one group of observers was not aware of the orientation of stimuli, whereas the other group was told beforehand that stimuli will be presented upside down. In experiment 2, independent groups of participants informed about stimulus orientation saw the same set of stimuli, in each of which either a moving or a static background line was inserted. The findings indicate that information about display inversion is insufficient for reliable recognition of inverted point-light biological motion. Instead, prior information facilitates display recognition only when it is complemented by additional contextual elements. It appears that visual impressions from inverted point-light stimuli remain impenetrable with respect to one's knowledge about display orientation. The origins of orientation specificity in biological motion perception are discussed in relation to the recent neuroimaging data obtained with point-light stimuli and fragmented Mooney faces.     

The effect of oxytocin on biological motion perception in dogs (<Emphasis Type="Italic">Canis familiaris</Emphasis>)

Recent studies have shown that the neuropeptide oxytocin is involved in the regulation of several complex human social behaviours. There is, however, little research on the effect of oxytocin on basic mechanisms underlying human sociality, such as the perception of biological motion. In the present study, we investigated the effect of oxytocin on biological motion perception in dogs (Canis familiaris), a species adapted to the human social environment and thus widely used to model many aspects of human social behaviour. In a within-subjects design, dogs (N = 39), after having received either oxytocin or placebo treatment, were presented with 2D projection of a moving point-light human figure and the inverted and scrambled version of the same movie. Heart rate (HR) and heart rate variability (HRV) were measured as physiological responses, and behavioural response was evaluated by observing dogs’ looking time. Subjects were also rated on the personality traits of Neuroticism and Agreeableness by their owners. As expected, placebo-pretreated (control) dogs showed a spontaneous preference for the biological motion pattern; however, there was no such preference after oxytocin pretreatment. Furthermore, following the oxytocin pretreatment female subjects looked more at the moving point-light figure than males. The individual variations along the dimensions of Agreeableness and Neuroticism also modulated dogs’ behaviour. Furthermore, HR and HRV measures were affected by oxytocin treatment and in turn played a role in subjects? looking behaviour. We discuss how these findings contribute to our understanding of the neurohormonal regulatory mechanisms of human (and non-human) social skills.     

无意识信息加工中的“完型”——无意识捆绑假说的新证据

采用连续闪烁范式(Continuous Flash Suppression,CFS)考察了无意识状态下完型能否发生.研究通过2(线条完整性)×2(意义破坏)×2(熟悉性)的被试内实验设计考察了8种条件下图片的突破抑制时间(Suppression Time,ST).结果发现:线条完整和意义未破坏的图片能更快地克服噪音图片的抑制进入意识;熟悉性不影响突破抑制时间.重要的是,不完整的图片也可以出现意义破坏效应.这表明即使在被抑制的状态下,不完整图形的信息也能够传达至与完型相关的高级视觉区域形成客体表征.研究为无意识捆绑假说(The Unconscious Binding Hypothesis)提供了新的实验证据.     

The relative importance of spatial versus temporal structure in the perception of biological motion: an event-related potential study

We investigated how the spatiotemporal structure of animations of biological motion (BM) affects brain activity. We measured event-related potentials (ERPs) during the perception of BM under four conditions: normal spatial and temporal structure; scrambled spatial and normal temporal structure; normal spatial and scrambled temporal structure; and scrambled spatial and temporal structure. As in a previous study, we identified two negative components at both occipitotemporal regions: N210 reflected general motion processing while N280 reflected the processing of BM. We analyzed the averaged ERPs in the 200-300 ms response time window and found that spatial structure had a substantial effect on the magnitude of the averaged response amplitude in both hemispheres. This finding suggests that spatial structure of point-lights elicits a stronger response in the occipitotemporal region than temporal structure for the BM perception.     

Effects of motion and audio-visual redundancy on upright and inverted face and feature preferences in 4-13-month old pre- and full-term NICU graduates

NICU infants are reported to have diminished social orientation and increased risk of socio-communicative disorders. In this eye tracking study, we used a preference for upright compared to inverted faces as a gauge of social interest in high medical risk full- and pre-term NICU infants. We examined the effects of facial motion and audio-visual redundancy on face and eye/mouth preferences across the first year. Upright and inverted baby faces were simultaneously presented in a paired-preference paradigm with motion and synchronized vocalization varied. NICU risk factors including birth weight, sex, and degree of CNS injury were examined. Overall, infants preferred the more socially salient upright faces, making this the first report, to our knowledge, of an upright compared to inverted face preference among high medical risk NICU infants. Infants with abnormalities on cranial ultrasound displayed lower social interest, i.e. less of a preferential interest in upright faces, when viewing static faces. However, motion selectively increased their upright face looking time to a level equal that of infants in other CNS injury groups. We also observed an age-related sex effect suggesting higher risk in NICU males. Females increased their attention to the mouth in upright faces across the first year, especially between 7–10 months, but males did not. Although vocalization increased diffuse attention toward the screen, contrary to our predictions, there was no evidence that the audio-visual redundancy embodied in a vocalizing face focused additional attention on upright faces or mouths. This unexpected result may suggest a vulnerability in response to talking faces among NICU infants that could potentially affect later verbal and socio-communicative development.     

Vestibular stimulation affects optic-flow sensitivity

Typically, multiple cues can be used to generate a particular percept. Our area of interest is the extent to which humans are able to synergistically combine cues that are generated when moving through an environment. For example, movement through the environment leads to both visual (optic-flow) and vestibular stimulation, and studies have shown that non-human primates are able to combine these cues to generate a more accurate perception of heading than can be obtained with either cue in isolation. Here we investigate whether humans show a similar ability to synergistically combine optic-flow and vestibular cues. This was achieved by determining the sensitivity to optic-flow stimuli while physically moving the observer, and hence producing a vestibular signal, that was either consistent with the optic-flow signal, eg a radially expanding pattern coupled with forward motion, or inconsistent with it, eg a radially expanding pattern with backward motion. Results indicate that humans are more sensitive to motion-in-depth optic-flow stimuli when they are combined with complementary vestibular signals than when they are combined with conflicting vestibular signals. These results indicate that in humans, like in nonhuman primates, there is perceptual integration of visual and vestibular signals.     

Temporal perception is enhanced for goal-directed biological actions

ABSTRACT

Research into the visual perception of goal-directed human action indicates that human action perception makes use of specialized processing systems, similar to those that operate in visual expertise. Against this background, the current research investigated whether perception of temporal information in goal-directed human action is enhanced relative to similar motion stimuli. Experiment 1 compared observers’ sensitivity to speed changes in upright human action to a kinematic control (an animation yoked to the motion of the human hand), and also to inverted human action. Experiment 2 compared human action to a non-human motion control (a tool moved the object). In both experiments observers’ sensitivity to detecting the speed changes was higher for the human stimuli relative to the control stimuli, and inversion in Experiment 1 did not alter observers’ sensitivity. Experiment 3 compared observers’ sensitivity to speed changes in goal-directed human and dog actions, in order to determine if enhanced temporal perception is unique to human actions. Results revealed no difference between human and dog stimuli, indicating that enhanced speed perception may exist for any biological motion. Results are discussed with reference to theories of biological motion perception and perception in visual expertise.     

Biological motion preference in humans at birth: role of dynamic and configural properties

The present study addresses the hypothesis that detection of biological motion is an intrinsic capacity of the visual system guided by a non-species-specific predisposition for the pattern of vertebrate movement and investigates the role of global vs. local information in biological motion detection. Two-day-old babies exposed to a biological motion point-light display (depicting a walking hen) and a non-biological motion display (a rotating rigid object) preferentially looked at the biological display (Experiment 1). A new group of newborns showed themselves to be capable of discriminating, following habituation, a biological motion display from a spatially scrambled version of it (Experiment 2). However, a third group of newborns, at their first exposure to such displays, did not show any preference between them (Experiment 3). Results confirm and extend previous comparative and developmental data, supporting an inborn predisposition to attend to biological motion in humans. This ability is presumably part of an evolutionarily ancient and non-species-specific system predisposing animals to preferentially attend to other animals.     

Do domestic dogs (<Emphasis Type="Italic">Canis lupus familiaris</Emphasis>) perceive the Delboeuf illusion?

In the last decade, visual illusions have been repeatedly used as a tool to compare visual perception among species. Several studies have investigated whether non-human primates perceive visual illusions in a human-like fashion, but little attention has been paid to other mammals, and sensitivity to visual illusions has been never investigated in the dog. Here, we studied whether domestic dogs perceive the Delboeuf illusion. In human and non-human primates, this illusion creates a misperception of item size as a function of its surrounding context. To examine this effect in dogs, we adapted the spontaneous preference paradigm recently used with chimpanzees. Subjects were presented with two plates containing food. In control trials, two different amounts of food were presented in two identical plates. In this circumstance, dogs were expected to select the larger amount. In test trials, equal food portion sizes were presented in two plates differing in size: if dogs perceived the illusion as primates do, they were expected to select the amount of food presented in the smaller plate. Dogs significantly discriminated the two alternatives in control trials, whereas their performance did not differ from chance in test trials with the illusory pattern. The fact that dogs do not seem to be susceptible to the Delboeuf illusion suggests a potential discontinuity in the perceptual biases affecting size judgments between primates and dogs.     

Visual preferences for sex and status in female rhesus macaques

Most primates are both highly visual and highly social. These qualities predict that visual cues to social variables, such as identity, sex, social status, and reproductive quality, would be intrinsically valuable and systematically attract attention. Supporting this idea, thirsty male rhesus macaques (Macaca mulatta) will forego fluid reward to view images of the faces of high-ranking males and the sexual skin of females. Whether female rhesus macaques, who experience dramatically different social pressures and reproductive costs than male macaques, also systematically and spontaneously value visual cues to social information remains untested experimentally. We probed the preferences of female rhesus macaques, given the opportunity to display an image from a known class of social stimuli or touch a second target to display a blank screen. We found that females preferred faces of high-status males and also images of the perinea of both males and females, but were not motivated to display images of subordinate males or control stimuli. These findings endorse the view that both male and female rhesus macaques—and presumably other highly social primates—seek information about other individuals in a way that matches the adaptive value of that information for guiding social behavior.     

MMPI–2 Profiles of Women With Eating Disorders in a Dutch Day Treatment Sample

This study tested two hypotheses concerning productivity and emotional tone as a function of chromatic TAT cards. Two groups of 13 males and 13 females were presented with achromatic and chromatic slides of cards 2, 3BM, 4, 6BM, and 7BM, in counterbalanced order. The main effects of sex membership, order of presentation of stimuli, and color were evaluated. Color did not have a measurable effect. However, a conceptual and aesthetic effect may occur. Males and females differed with respect to emotional tone and response productivity.     

Visual perception of biological motion in newly hatched chicks as revealed by an imprinting procedure

Day-old chicks were exposed to point-light animation sequences depicting either a walking hen or a rotating cylinder. On a subsequent free-choice test (experiment 1) the chicks approached the novel stimulus, irrespective of this being the hen or the cylinder. In order to obtain equivalent local motion vectors, in experiments 2 and 3 newly hatched chicks were exposed either to a point-light animation sequence depicting a walking hen, or to a positionally scrambled walking hen (i.e. an animation in which exactly the same set of dots in motion as that employed for the walking hen was presented, but with spatially randomized starting positions). Chicks tested on day 1 (experiment 2) or on day 2 (i.e. after a period in the dark following exposure on day 1 (experiment 3)) proved able to discriminate the two animation sequences: males preferentially approached the novel stimulus, females the familiar one. These results indicate that discrimination was not based on local motion vectors, but rather on the temporally integrated motion sequence. Received: 18 August 1999 / Accepted after revision: 14 March 2000     

Speech dominance and handedness in the normal human

Spectral analysis was used to measure the coherence or similarity of form between occipital and temporal evoked potentials. In both right- and left-handers, coherence was greater in the left hemisphere for click stimuli and in the right hemisphere for flash stimuli. Similar asymmetries occurred in left but not right speech dominant patients whose speech lateralization has been determined by the intracarotid amytal test. Right-handers and males, however, showed significantly larger amplitudes of auditory responses in the right hemisphere. Left-handers and females reversed this pattern. It was concluded that within a basically left speech dominant organization, males and right-handers would emphasize the verbal, temporal structure of auditory information and the nonverbal, spatial structure of visual information. Females and left-handers would tend to reverse this emphasis.