The psychophysics of bouncing: Perceptual constraints, physical constraints, animacy, and phenomenal causality.

In the present study we broadly explored the perception of physical and animated motion in bouncing-like scenarios through four experiments. In the first experiment, participants were asked to categorize bouncing-like displays as physical bounce, animated motion, or other. Several parameters of the animations were manipulated, that is, the simulated coefficient of restitution, the value of simulated gravitational acceleration, the motion pattern (uniform acceleration/deceleration or constant speed) and the number of bouncing cycles.

Perceiving animacy from kinematics: visual specification of life-likeness in simple geometric patterns.

Since the seminal work of Heider and Simmel, and Michotte's research, many studies have shown that, under appropriate conditions, displays of simple geometric shapes elicit rich and vivid impressions of animacy and intentionality. The main purpose of this review is to emphasize the close relationship between kinematics and perceived animacy by showing which specific motion cues and spatiotemporal patterns automatically trigger visual perceptions of animacy and intentionality. The animacy phenomenon has been demonstrated to be rather fast, automatic, irresistible, and highly stimulus-driven.

Speed Overestimation of the Moving Away Object in the Causal Effect.

We describe a new illusory speed effect arising in visual events developed by Michotte (1946/1963) in studies of causal perception and, more specifically, within the so-called : When an Object is seen intentionally escaping from another Object , its perceived speed is overestimated. In Experiment 1, we used two-alternative forced choice comparisons to estimate perceived speed scale values for a small square moving either alone or in different contexts known to elicit different impressions of animacy (Parovel et al., 2018).

Increasing Perspectival Obliqueness Increases the Leaning Tower Illusion.

The leaning tower illusion is a perceptual illusion in which two identical images of a tower photographed from below appear to diverge when juxtaposed. We manipulated the perceived obliqueness of the (upright) St Mark bell tower in Venice by modifying two parameters both related to the position of the camera with respect to the tower: (a) increasing the peripherality of the tower and (b) reducing the distance between the camera and the tower. The resulting images clearly show that the illusory leaning effect increases as a function of the obliqueness.

Different contexts change the impression of animacy.

The aim of this research was to explore the effect of different spatiotemporal contexts on the perceptual saliency of animacy, and the extent of the relationship between animacy and other related properties such as emotions and intentionality. Paired-comparisons and ratings were used to compare the impressions of animacy elicited by a small square moving on the screen, either alone or in the context of a second square. The context element was either static or moving showing an animate-like or a physical-like trajectory, and the target object moved either toward it or away from it.

The psychophysics of comic: Effects of incongruity in causality and animacy.

According to several theories of humour (see Berger, 2012; Martin, 2007), incongruity - i.e., the presence of two incompatible meanings in the same situation - is a crucial condition for an event being evaluated as comical.

The emotional effects of violations of causality, or How to make a square amusing.

In Michotte's launching paradigm a square moves up to and makes contact with another square, which then moves off more slowly. In the triggering effect, the second square moves much faster than the first, eliciting an amusing impression. We generated 13 experimental displays in which there was always incongruity between cause and effect.

Perceived shrinkage of motion paths.

We show that human observers strongly underestimate a linear or circular trajectory that a luminous spot follows in the dark. At slow speeds, observers are relatively accurate, but, as the speed increases, the size of the path is progressively underestimated, by up to 35%. The underestimation imposes little memory load and does not require tracking of the trajectory.

The psychophysical law of speed estimation in Michotte's causal events.

Observers saw an event in which a computer-animated square moved up to and made contact with another, which after a short delay moved off, its motion appearing to be caused by launch by the first square. Observers chose whether the second (launched) square was faster in this causal event than when presented following a long delay (non-causal event). The speed of the second object in causal events was overestimated for a wide range of speeds of the first object (launcher), but accurately assessed in non-causal events.

Mirror symmetry opposes splitting of chromatically homogeneous surfaces.

Chromatically homogeneous surfaces can be seen as single figures but also as two or more overlapping figures. Local factors such as relatability have been proposed in order to explain perception of two or more figures (Kellman and Shipley, 1991 Cognitive Psychology 23 141-221). However, even when these factors are at work, there are conditions favouring the perception of a single figure, which have not been explored so far.