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Age-related differences on theory of mind (ToM) tasks are well established. However, the literature has been criticised for predominantly relying on tasks with poor ecological validity, and consequently it remains unclear whether these age differences extend to tasks with greater realism. In addition, we currently have a limited understanding of the factors that may contribute to age-related declines in ToM. To address these issues, we conducted two studies that assessed age differences in ToM using multimodal social scene stimuli. Study 1 also examined eye movements to assess whether biases in visual attention may be related to age-related difficulties in ToM, and Study 2 included an assessment of social attention (as indexed by biological motion perception) and working memory to assess whether these capacities may explain age difficulties in ToM. In both studies, the results showed that older adults performed worse than their younger counterparts on the ToM tasks, indicating that age-related difficulties in ToM extend to measures that more closely represent everyday social interactions. The eye-tracking data in Study 1 showed that older adults gazed less at the faces of protagonists in the social scenes compared with younger adults; however, these visual biases were not associated with ToM ability. Study 2 showed that older age was associated with a reduced ability to detect biological motion cues, and this mediated age-related variance in ToM ability. These findings are discussed in relation to competing theoretical frameworks of ageing that predict either improvements or declines in ToM with age.

In a cartoon, we often receive an animacy impression from a dynamic nonanimate object, such as a sponge or a flour sack, which does not have an animal-like shape. We hypothesize that the animacy impression of a nonanimal object could stem from dynamic patterns that are possibly fundamental for biological motion perception. Here we show that observers recognize the animacy of human jump actions from the combination of deformation and translation. We extracted vertical motion vectors from the uppermost and lowermost points in point-light jumper stimuli and assigned the vectors to a uniform rectangle. The participants’ task was to rate the animacy and jump impressions for the rectangle. Results showed that both animacy and jump impressions for the rectangle movements were comparable to those for the original point-light movements. The impressions decreased for stimuli having a deformation or translation component alone, which was extracted from the original motion vectors. By mathematically simulating deformation and translation in a human jump, we also found that the temporal relation between deformation and translation plays a critical role in the determination of jump impressions but only has a moderate effect for animacy impressions. On the basis of the results, we discuss how cartoon techniques take advantage of the properties of biological motion perception.

The “body inversion effect” refers to superior recognition of upright than inverted images of the human body and indicates typical configural processing. Previous research by Reed et al. using static images of the human body shows that people with autism fail to demonstrate this effect. Using a novel task in which adults, adolescents with autism, and typically developing adolescents judged whether walking stick figures—created from biological motion recordings and shown at seven orientations between 0° and 180°—were normal or distorted, this study shows clear effects of stimulus inversion. Reaction times and “inverse efficiency” increased with orientation for normal but not distorted walkers, and sensitivity declined with rotation from upright for all groups. Notably, the effect of stimulus inversion was equally detrimental to both groups of adolescents suggesting intact configural processing of the body in motion in autism spectrum disorder.

The presence of information in a visual display does not guarantee its use by the visual system. Studies of inversion effects in both face recognition and biological-motion perception have shown that the same information may be used by observers when it is presented in an upright display but not used when the display is inverted. In our study, we tested the inversion effect in scrambled biological-motion displays to investigate mechanisms that validate information contained in the local motion of a point-light walker. Using novel biological-motion stimuli that contained no configural cues to the direction in which a walker was facing, we found that manipulating the relative vertical location of the walker’s feet significantly affected observers’ performance on a direction-discrimination task. Our data demonstrate that, by themselves, local cues can almost unambiguously indicate the facing direction of the agent in biological-motion stimuli. Additionally, we document a noteworthy interaction between local and global information and offer a new explanation for the effect of local inversion in biological-motion perception.

We tested the ability of children 3–5 years of age to recognise biological motion displays. Children and adults were presented with moving point-light configurations depicting a walking person, four-legged animals (dogs), and a bird. Participants were able to reliably recognise displays with biological motion, but failed in the identification of a static (four consecutive frames taken from each sequence) version. The results indicate that, irrespective of the highly reduced and unusual structural information available in point-light displays, biological motion is sufficient for reliable recognition of human and non-human forms at an age as early as 3 years. Moreover, 5-year-olds exhibit the ceiling level of recognition. The findings are discussed in the context of the neuropsychological and brain mechanisms involved in biological motion perception.

It is well known that biological motion, as produced by point-light displays on a human body, gives a good representation of the represented body—eg its gender and the nature of the task which it is engaged in. The question is whether it is possible to judge the emotional state of a human body from motion information alone. An ability to make this kind of judgment may imply that people are able to perceive emotion from patterns of movement without having to compute the detailed shape first. Subjects were shown brief video clips of two trained dancers (one male, one female). The dancers were aiming to convey the following emotions: fear, anger, grief, joy, surprise, and disgust. The video clips protrayed fully lit scenes and point-light scenes, with thirteen small points of light attached to the body of each dancer. Half the stimuli were presented the right way up, while half were inverted. The subjects' task was to judge which emotion was being portrayed. Full-body clips gave good recognition of emotionality (88% correct), but the results for upright biological-motion displays were also significantly above chance (63% correct). Inversion of the display reduced biological-motion (but not full-body) performance to close to chance but still significantly above chance. A space–time analysis of the motion of the points of light was carried out, and was related to the discriminability of the different emotions. Biological-motion displays, which convey no information while static, are able to give a rich description of the subject matter, including the ability to judge emotional state. This ability is disrupted when the image is inverted.

The structure of the human form is quickly and unequivocably recognized from 10 to 13 points of light moving as if attached to the major joints and head of a person walking Recent psychophysical and computational models of this process suggest that these displays are organized by low-level processing constraints that delimit the pair-wise connections of the point lights In the current research, these low-level constraints were rendered uninformative by a masking paradigm The results from four experiments converged to show that the perception of structure in a point-light walker display does not require the prior detection of individual features or local relations

Typically developing adults can readily recognize human actions, even when conveyed to them via point-like markers placed on the body of the actor (Johansson, 1973). Previous research has suggested that children affected by autism spectrum disorder (ASD) are not equally sensitive to this type of visual information (Blake et al, 2003), but it remains unknown why ASD would impact the ability to perceive biological motion. We present evidence which looks at how adolescents and adults with autism are affected by specific factors which are important in biological motion perception, such as (eg, inter-agent synchronicity, upright/inverted, etc).

How does biological motion perception change with display orientation? As previously shown, display inversion (180°) completely prevents veridical perception of biological motion. However, with upright orientation (0°), observers are able to recover the invariant structure through biological motion despite reverse transformation (showing the film backwards) or changing the presentation rate (Pavlova, 1995 Perception24 Supplement, 112). In the present experiments, observers saw the biological motion pattern at various display deviations, from inverted to upright orientation (180°, 150°, 120°, 90°, 60°, 30°, 0°), in the right or left hemifield, on a circular screen monitor. The display consisted of an array of 11 dots on the main joints of an invisible walker moving as if on a treadmill. While viewing (60 s), observers pressed a key each time their perception changed from one stable percept to another (eg when the direction of apparent rotation of the pattern reversed). The perceived multistability (the number of key-presses) increased as orientation was varied from inverted to 90°, and then decreased between 90° and upright. The recognition of walking figure improved abruptly with changing orientation: at deviations of 60° and 30° most observer reported seeing the walking figure spontaneously, yet the pattern was seen as multistable. The findings imply the relative power of constraints (such as orientation) in perception of biological motion that is discussed in relation to the KSD principle in event perception [Runeson, 1994, in Perceiving Events and Objects Eds Jansson, Epstein, Bergström (Hillsdale, NJ: Erlbaum) pp 383 – 405].

In a film produced by Johansson, a group of moving spots, corresponding to lights attached to the main joints of a walker or a runner, gives instantly a vivid impression of a person walking or running. Even when this film was inverted and run backward, some sort of human movement was still perceived. It was perceived more frequently as an upright image of a person moving forward in a very strange manner than as an inverted image of a person moving backward. Such strangeness seemed to arise from the fact that the actor's arms were perceived as legs and vice versa. The phase relations typical of the Johansson pattern are therefore still present when the film is inverted and run backward, leading to the perception of biological motions though these motions are very strange.