Despite its popularity, the construct of biological motion (BM) and its putative anomalies in autism spectrum disorder (ASD) are not completely clarified. In this article, we present a meta-analysis investigating the putative anomalies of BM perception in ASD. Through a systematic literature search, we found 30 studies that investigated BM perception in both ASD and typical developing peers by using point-light display stimuli. A general meta-analysis including all these studies showed a moderate deficit of individuals with ASD in BM processing, but also a high heterogeneity. This heterogeneity was explored in different additional meta-analyses where studies were grouped according to levels of complexity of the BM task employed (first-order, direct and instrumental), and according to the manipulation of low-level perceptual features (spatial vs. temporal) of the control stimuli. Results suggest that the most severe deficit in ASD is evident when perception of BM is serving a secondary purpose (e.g., inferring intentionality/action/emotion) and, interestingly, that temporal dynamics of stimuli are an important factor in determining BM processing anomalies in ASD. Our results question the traditional understanding of BM anomalies in ASD as a monolithic deficit and suggest a paradigm shift that deconstructs BM into distinct levels of processing and specific spatio-temporal subcomponents.

According to the spatial–temporal association of response codes (STEARC) effect, time can be spatially represented from left to right. However, exploration of a possible STEARC effect along the vertical axis has yielded mixed results. Here, in six experiments based on a novel paradigm, we systematically explored whether a STEARC effect could emerge when participants were asked to classify the actual temporal duration of a visual stimulus. Speeded manual responses were provided using a vertically oriented response box. Interestingly, although a top-to-bottom time representation emerged when only two temporal durations were employed, an inverted bottom-to-top time representation emerged when a denser set of temporal durations, arranged along a continuum, was used. Moreover, no STEARC effects emerged when participants classified the shapes of visual stimuli rather than their temporal duration. Finally, three additional experiments explored the STEARC effect along the horizontal axis, confirming that the paradigm we devised successfully replicated the standard left-to-right representation of time. These results provide supporting evidence for the notion that temporal durations can be mapped along the vertical axis, and that such mapping appears to be relatively flexible.

No abstract

Stimuli associated with large quantities are typically responded to faster with a right-than a left-side key, whereas stimuli associated with small quantities are typically responded to faster with a left-than a right-side key. This phenomenon is known as the spatial-quantity association of response codes (SQUARC) effect. Here, in two experiments, we explored whether a SQUARC effect can emerge for light versus heavy items. Participants judged whether the weight associated with a central target word, describing an animal (e.g. 'cow'; Experiment 1) or a material (e.g. 'iron'; Experiment 2), was lighter or heavier than the weight associated with a reference word. Responses were provided with a left-and a right-side button. Then, participants estimated the weight associated with target and reference words. In both experiments, evidence for a SQUARC effect emerged. Moreover, response times for each target word decreased with absolute difference between its rated weight and the rated weight of the reference word, in line with a distance effect. Overall, these results provide evidence of a possible spatial representation of weight.

Because the perceived weight of objects may be affected by various nonweight properties, such as their size and the density of their surface material, relative weight is sometimes misperceived (the size-weight illusion and the material-weight illusion, respectively). A widely accepted explanation for weight illusions is provided by the so-called expectation model, according to which the perceived weight stems from the contrast between the actual and expected weights. In the present study, we varied both the surface material and the size of stimuli, while keeping constant their physical weights. In Experiment 1, the participants lifted the stimuli by grasping them on opposite sides, whereas in Experiment 2 they lifted them by using a string that was attached to their top surface. We used a variant of the random conjoint measurement paradigm to obtain subjective interval scales of the contributions of surface material and size to the expected and the perceived weight of the stimuli. Inconsistently with the predictions from the expectation model, we found, in both experiments, that the surface material contributed more than the size to the expected weight, whereas the size contributed more than the surface material to the perceived weight. The results support the hypothesis that perceived weight may depend on implicit, rather than explicit, weight expectations.

No abstract

The magnitude associated with a stimulus can be spatially connoted, with relatively smaller and larger magnitudes that would be represented on the left and on the right side of space, respectively. According to recent evidence, this space–magnitude association could reflect specific brain asymmetries. In this study, we explored whether such an association can also emerge for face age, assuming that responders should represent relatively younger and older adult faces on the left and on the right, respectively. A sample of young adults performed a speeded binary classification task aimed at categorising the age of a centrally placed adult face stimulus as either younger or older than the age of a reference face. A left-side and a right-side response key were used to collect manual responses. Overall, older faces were categorised faster than younger faces, and response latencies decreased with the absolute difference between the age of the target stimulus and the age of the reference, in line with a distance effect. However, no evidence of a left-to-right spatial representation of face age emerged. Taken together, these results suggest that face age is mapped onto space differently from other magnitudes.

No abstract