Optical flow and viewpoint change modulate the perception and memorization of complex motion

Participants observed a point-light character (PLC) performing a gymnastic movement. They either memorized the final PLC orientation from the initial viewpoint, to match it to a test posture (memory task), or judged whether the biological motion appeared continuous (perceptual task), despite a viewpoint change. The observer could be either static or virtually in motion (pan or track) while looking at the movement from the initial viewpoint. The presence of a spatial layout during virtual self-motion induced a global optical flow specifying the translational component of the PLC movement, rendering the event more predictable for the participants. A representational momentum effect was observed in the memory task, suggesting that when a visual stimulation, such as a PLC motion, is abruptly stopped, its dynamics survive. In contrast, structural and transformational invariants specifying the PLC motion were sufficient to solve the perceptual task accurately. Finally, both the remembering of the final posture and the perception of continuity degraded with an increase in viewpoint change due to tilt/slant posture orientation matching, indicating that orientation processes interfered with event perception.     

Conscious knowledge and changes in performance in sequence learning: evidence against dissociation.

Two experiments examined the relation between explicit knowledge and motor performance on the serial reaction time task developed by Nissen and Bullemer (1987). Tests of free recall and recognition of sequence components revealed that reliable explicit knowledge was acquired after an amount of practice that was hardly sufficient to improve mean motor performance. In addition, reaction time improvement was limited to the ending trials of the 3- and 4-trial sequence components that Ss recalled or recognized. These results were replicated in Experiment 3, in which Ss were trained under attentional distraction in the task developed by Cohen, Ivry, and Keele (1990). Overall, these findings undermine the most direct experimental support for the widespread view that conscious knowledge and performance in sequence-learning tasks tap 2 independent knowledge bases in normal Ss.     

Empathy deficits and trait emotional intelligence in psychopathy and Machiavellianism

This study investigated the relationships between psychopathy (primary and secondary), Machiavellianism, trait emotional intelligence and empathy, using an image task that required an appropriate empathic response to the emotional displays of others (happy, sad and neutral). Results indicated that primary psychopathy and Machiavellianism were positively associated with the experience of positive affect from sad stimuli, while secondary psychopathy and Machiavellianism were positively associated with the experience of negative affect in response to neutral stimuli, and the opposite pattern was found for trait emotional intelligence. Regressional analyses demonstrated that secondary psychopathy, Machiavellianism, trait emotional intelligence and state anxiety are important predictors when stimuli are ambiguous.     

Is the sunny side up and the dark side down? Effects of stimulus type and valence on a spatial detection task

In verbal communication, affective information is commonly conveyed to others through spatial terms (e.g. in “I am feeling down”, negative affect is associated with a lower spatial location). This study used a target location discrimination task with neutral, positive and negative stimuli (words, facial expressions, and vocalizations) to test the automaticity of the emotion-space association, both in the vertical and horizontal spatial axes. The effects of stimulus type on emotion-space representations were also probed. A congruency effect (reflected in reaction times) was observed in the vertical axis: detection of upper targets preceded by positive stimuli was faster. This effect occurred for all stimulus types, indicating that the emotion-space association is not dependent on sensory modality and on the verbal content of affective stimuli.     

The perception of visually presented yaw and pitch turns: assessing the contribution of motion, static, and cognitive cues

Terrestrial gravity restricts human locomotion to surfaces in which turns involve rotationsaround the body axis. Because observers are usually upright, one might expect the effects of gravity to induce differences in the processing of vertical versus horizontal turns. Subjects observed visual scenes of bending tunnels, either statically or dynamically, as if they were moving passively through the visual scene and were then asked to reproduce the turn deviation of the tunnel with a trackball. In order to disentangle inertia-related (earth-centered) from vision-related (body-centered) factors, the subjects were either upright or lying on their right side during the observations. Furthermore, the availability of continuous optic flow, geometrical cues, and eye movement were manipulated in three experiments. The results allowed us to characterize the factors' contributions as follows. Forward turns (pitch down) with all cues were largely overestimated, as compared with backward turns (pitch up). First, eye movements known to be irregular for vertical stimulation were largely responsible for this asymmetry. Second, geometry-based estimations are, to some extent, asymmetrical. Third, a cognitive effect corresponding to the evaluation of navigability for upward and downward turns was found (i.e.,top-down influences, such as the fear of falling often reported), which tended to increase the estimation of turns in the direction of gravity.     

Motion prediction and the velocity effect in children

In coincidence‐timing studies, children have been shown to respond too early to slower stimuli and too late to faster stimuli. To examine this velocity effect, children aged 6, 7.5, 9, 10.5, and adults were tested with two different velocities in a prediction‐motion task which consisted of judging, after the occlusion of the final part of its path, the moment of arrival of a moving stimulus towards a specified position. A similar velocity effect, resulting in later responses for the faster velocities than for the slower, was found primarily in the three younger groups of children (for the longer occlusion conditions: 600–1,320 milliseconds). However, this effect was not seen in all children in these groups. Individual analyses showed that this velocity effect, when present, is linked to the use of distance rather than time information, or to the confusion between these in extrapolating the occluded trajectories. The tendency to use one type of information or the other is a good predictor of accuracy and variability in this task and a good indicator of the development stage of the participants. Across development, children tend to initially use distance information with poor accuracy but relative consistency in responses. In a second stage, they use time and distance information alternatively across trials trying to find a better source of information with still poor accuracy and now great variability. In a final stage, they use time information to reach consistency and accuracy in their responses. This chronology follows the stages proposed by Savelesbergh and Van der Kamp (2000) explaining development with an initial stage of ‘freezing’ non‐optimal relationships between information and movement, then a ‘freeing’ stage during which new solutions are searched for, and finally an ‘exploiting’ stage with an optimal relationship between information and movement.