Effects of Audiovisual Presentations on Visual Localization Errors: One or Several Multisensory Mechanisms?

The present study examines the extent to which temporal and spatial properties of sound modulate visual motion processing in spatial localization tasks. Participants were asked to locate the place at which a moving visual target unexpectedly vanished. Across different tasks, accompanying sounds were factorially varied within subjects as to their onset and offset times and/or positions relative to visual motion. Sound onset had no effect on the localization error. Sound offset was shown to modulate the perceived visual offset location, both for temporal and spatial disparities. This modulation did not conform to attraction toward the timing or location of the sounds but, demonstrably in the case of temporal disparities, to bimodal enhancement instead. Favorable indications to a contextual effect of audiovisual presentations on interspersed visual-only trials were also found. The short sound-leading offset asynchrony had equivalent benefits to audiovisual offset synchrony, suggestive of the involvement of early-level mechanisms, constrained by a temporal window, at these conditions. Yet, we tentatively hypothesize that the whole of the results and how they compare with previous studies requires the contribution of additional mechanisms, including learning-detection of auditory-visual associations and cross-sensory spread of endogenous attention.

Representational momentum in dynamic facial expressions is modulated by the level of expressed pain: Amplitude and direction effects.

Humans have developed a specific capacity to rapidly perceive and anticipate other people's facial expressions so as to get an immediate impression of their emotional state of mind. We carried out two experiments to examine the perceptual and memory dynamics of facial expressions of pain. In the first experiment, we investigated how people estimate other people's levels of pain based on the perception of various dynamic facial expressions; these differ both in terms of the amount and intensity of activated action units. A second experiment used a representational momentum (RM) paradigm to study the emotional anticipation (memory bias) elicited by the same facial expressions of pain studied in Experiment 1. Our results highlighted the relationship between the level of perceived pain (in Experiment 1) and the direction and magnitude of memory bias (in Experiment 2): When perceived pain increases, the memory bias tends to be reduced (if positive) and ultimately becomes negative. Dynamic facial expressions of pain may reenact an "immediate perceptual history" in the perceiver before leading to an emotional anticipation of the agent's upcoming state. Thus, a subtle facial expression of pain (i.e., a low contraction around the eyes) that leads to a significant positive anticipation can be considered an adaptive process-one through which we can swiftly and involuntarily detect other people's pain.

Spatial and foveal biases, not perceived mass or heaviness, explain the effect of target size on representational momentum and representational gravity.

The spatial memory for the last position occupied by a moving target is usually displaced forward in the direction of motion. Interpreted as a mental analogue of physical momentum, this phenomenon was coined representational momentum (RM). As momentum is given by the product of an object's velocity and mass, both these factors came to be under scrutiny in RM studies, the goal being to provide support for the internalization hypothesis. Although velocity was found to determine RM's magnitude, possible effects of mass were more elusive. Recently, an effect of target size on RM was reported, adding to previous findings that bigger targets were more mislocalized downward in the direction of gravity (via perceived heaviness and representational gravity; RG). The aim in the present research was to test that those outcomes reflect an internalization of momentum by excluding oculomotor factors. The results showed that an effect of target size, when it emerged, could be accounted for by a foveal bias such that bigger targets were more displaced toward gaze than were smaller ones. Specific contingencies between eye movements and target size seem to account for previous reports regarding the alleged effects of perceived mass on both RM and RG. This phenomenon seems furthermore to be modulated by the presence of other visual elements (fixation point) and the range of target velocities. These outcomes are taken as a rebuttal to the claim that cognitive analogues of mass or heaviness are responsible for previously reported effects of target size on both RM and RG.

The representational dynamics of remembered projectile locations.

When people are instructed to locate the vanishing location of a moving target, systematic errors forward in the direction of motion (M-displacement) and downward in the direction of gravity (O-displacement) are found. These phenomena came to be linked with the notion that physical invariants are embedded in the dynamic representations generated by the perceptual system. We explore the nature of these invariants that determine the representational mechanics of projectiles. By manipulating the retention intervals between the target's disappearance and the participant's responses, while measuring both M- and O-displacements, we were able to uncover a representational analogue of the trajectory of a projectile. The outcomes of three experiments revealed that the shape of this trajectory is discontinuous. Although the horizontal component of such trajectory can be accounted for by perceptual and oculomotor factors, its vertical component cannot. Taken together, the outcomes support an internalization of gravity in the visual representation of projectiles.

Explorando a trajetória espácio-temporal da representação dinâmica de projéteis / Exploring the spatiotemporal trajectory of the dynamic representation of projectiles

Quando é mostrado a observadores humanos um objeto em movimento horizontal que desaparece subitamente, e se instruídos a indicar o local de desaparecimento, emerge sistematicamente um erro para diante na direção do movimento (Desfasamento M) e para baixo na direção da gravidade (Desfasamento O). Ainda que diversos determinantes do fenómeno estejam bem documentados, pouco é ainda sabido acerca do seu curso temporal. O presente estudo procura preencher esta lacuna. Objetos descrevendo movimentos horizontais foram mostrados a participantes instruídos a indicarem o seu local de desaparecimento, usando ou um mouse ou um ponteiro (num ecrã táctil), após um intervalo de retenção variado. Os resultados revelaram uma trajetória ordenada para os erros de localização em função do tempo, passível de ser descrita em duas fases - numa primeira, até cerca de 300ms, os erros progrediram para diante sem qualquer desfasamento vertical; após os 300ms o erro tende a aumentar na direção descendente sem qualquer incremento horizontal. Paralelos deste padrão com tarefas de física intuitiva (Física de Road Runner) e antecedentes na História Pré-Galilaica da Física são referidos e os resultados discutidos no âmbito de uma representação implícita de invariantes físicos na perceção de eventos dinâmicos.(AU)

When human observers are shown a horizontally moving target which suddenly disappears and they are further instructed to locate its vanishing position, both forward in the direction of motion (M Displacement) and downward in the direction of gravity (O Displacement), errors of localization typically occur. Though several determinants of those errors have been ascertained, little is known regarding their time course. The present study attempts to fill this gap. Horizontally moving targets were presented and participants instructed to locate their vanishing position, either via a mouse or a pointer (on a touch screen) after a variable time delay. Outcomes revealed an orderly time-dependent trajectory of errors being describable in two stages - during the first 300ms, the errors increased in the direction of motion with a constant vertical error; after 300ms the downward error increased with no further horizontal displacement. Similarities between this pattern and reported results from the Intuitive Physics (Road Runner Physics) and the History of Ancient Physics are noticed and discussed under the notion of an implicit representation of physical invariants in the perception of dynamic events.(AU)

Explorando a trajetória espácio-temporal da representação dinâmica de projéteis / Exploring the spatiotemporal trajectory of the dynamic representation of projectiles

Quando é mostrado a observadores humanos um objeto em movimento horizontal que desaparece subitamente, e se instruídos a indicar o local de desaparecimento, emerge sistematicamente um erro para diante na direção do movimento (Desfasamento M) e para baixo na direção da gravidade (Desfasamento O). Ainda que diversos determinantes do fenómeno estejam bem documentados, pouco é ainda sabido acerca do seu curso temporal. O presente estudo procura preencher esta lacuna. Objetos descrevendo movimentos horizontais foram mostrados a participantes instruídos a indicarem o seu local de desaparecimento, usando ou um mouse ou um ponteiro (num ecrã táctil), após um intervalo de retenção variado. Os resultados revelaram uma trajetória ordenada para os erros de localização em função do tempo, passível de ser descrita em duas fases - numa primeira, até cerca de 300ms, os erros progrediram para diante sem qualquer desfasamento vertical; após os 300ms o erro tende a aumentar na direção descendente sem qualquer incremento horizontal. Paralelos deste padrão com tarefas de física intuitiva (Física de Road Runner) e antecedentes na História Pré-Galilaica da Física são referidos e os resultados discutidos no âmbito de uma representação implícita de invariantes físicos na perceção de eventos dinâmicos...

When human observers are shown a horizontally moving target which suddenly disappears and they are further instructed to locate its vanishing position, both forward in the direction of motion (M Displacement) and downward in the direction of gravity (O Displacement), errors of localization typically occur. Though several determinants of those errors have been ascertained, little is known regarding their time course. The present study attempts to fill this gap. Horizontally moving targets were presented and participants instructed to locate their vanishing position, either via a mouse or a pointer (on a touch screen) after a variable time delay. Outcomes revealed an orderly time-dependent trajectory of errors being describable in two stages - during the first 300ms, the errors increased in the direction of motion with a constant vertical error; after 300ms the downward error increased with no further horizontal displacement. Similarities between this pattern and reported results from the Intuitive Physics (Road Runner Physics) and the History of Ancient Physics are noticed and discussed under the notion of an implicit representation of physical invariants in the perception of dynamic events...