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The effect of different sounds on visual apparent movement
No full textAccording to Werner's hypothesis (Zietz and Werner, 1928 Zeitschrift fÏr Psychologie 105 226 ^ 249), the phenomenal concomitance of two dynamic events (visual and auditory) gives rise to an intermodal unitary event. Zietz and Werner showed that a hardly noticeable apparent movement of a visual stimulus became more evident when a sound event was presented simulta- neously. Other authors, for example Staal and Donderi (1983 American Journal of Psychology 1 95 ^ 105), did not always obtain the same results.
The purpose of the present work was to investigate the effect of different sounds on a visual bistable event: two different apparent movements can be seen inside a black frame: a `phi' move- ment, ie a small square moving from left to the right, or a `gamma' polarised movement, ie an expansion of the small square toward the centre of the frame from both sides in succession. I used (i) continuous, (ii) increasing and (iii) decreasing in frequency sounds, and (iv) two short sounds in succession. `Gamma' polarised movement was seen only in the latter condition. On the other hand, the degree of visibility of the `phi' movement increased by adding sound with dynamic qualities (increasing and decreasing in frequency).
These results are in accord with Werner's hypothesis; a greater probability of one perceptual solution compared to the other was observed when the auditory and the visual events were phenomenally congruent
Speed Overestimation in Chasing Events
No full textMany studies show an association between speed and animacy: objects moving faster tend to be judged as more animated. We explored the effect of different contexts on speed perception of objects with different degrees of animacy. Paired-comparisons were used to compare the perceived speed of a square moving on the screen alone or in the context of a second square. The context element was either static or moved showing an animate-like or a physical-like trajectory, and the target moved toward it or away from it, always at the same physical speed. Results showed that the target perceived speed was greater in some of the contexts in which it was seen as more alive. The effect, however, was only significant when the target was moving away from the context square and the context square showed an animate-like trajectory, suggesting a specific association between speed and chasing, but not between speed and animacy tout court
Does an escaping object look faster? Animacy induced speed overestimation in chasing events
No full textIn Michotte's paradigm an object A moves toward, and makes contact with, another object B, which then moves away. If B’s motion is faster than A’s, and starts before the arrival of A, B is perceived to intentionally escape from A. Many studies show an association between speed and animacy, in that objects moving faster are judged as more animated. In our study, conversely, we explored how much a square looks faster when intentionally escaping from another square. We used the method of constant stimuli to measure the speed overestimation of the escaping object in comparison to different levels of speed of a single moving object. We also varied the behaviour of the chasing object, allowing it to move either in a linear or in a caterpillar-like way. Paired comparisons data were analysed using generalized linear mixed-effects models to estimate the PSE in the different conditions. We found a significant overestimation of the escaping object in the fast speed condition, both in the caterpillar-like motion and in the linear motion. These results suggest an interesting connection between specific emotional qualities of motion and its apparent speed, supporting the hypothesis that social causality and animacy are deeply rooted in visual processing
The emotional effects of violations of causality or How to make a square amusing
No full textIn 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. We hypothesized that the comic impression would be stronger when objects are perceived as living agents and weaker when objects are perceived as mechanically non-animated. General findings support our hypothesis
The psychophysics of bouncing: Perceptual constraints, physical constraints, animacy, and phenomenal causality
Full text linkIn 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. In the second experiment, a variable delay at the moment of the collision between the bouncing object and the bouncing surface was introduced. Main results show that, although observers appear to have realistic representations of physical constraints like energy conservation and gravitational acceleration/deceleration, the amount of visual information available in the scene has a strong modulation effect on the extent to which they rely on these representations. A coefficient of restitution >1 was a crucial cue to animacy in displays showing three bouncing cycles, but not in displays showing one bouncing cycle. Additionally, bouncing impressions appear to be driven by perceptual constraints that are unrelated to the physical realism of the scene, like preference for simulated gravitational attraction smaller than g and perceived temporal contiguity between the different phases of bouncing. In the third experiment, the visible opaque bouncing surface was removed from the scene, and the results showed that this did not have any substantial effect on the resulting impressions of physical bounce or animated motion, suggesting that the visual system can fill-in the scene with the missing element. The fourth experiment explored visual impressions of causality in bouncing scenarios. At odds with claims of current causal perception theories, results indicate that a passive object can be perceived as the direct cause of the motion behavior of an active object
The larger the cause, the larger the effect: evidence of speed judgment biases in causal scenarios
No full textWhen two motions appear to be causally related, the spatiotemporal features of motions are sometimes distorted in order to increase the consistency with causal impressions. Here, in four experiments, we tested if varying the speed of an object A could affect the judged speed of an object B that appeared to be causally related to A. Participants were presented with classic launching stimuli (Experiment 1), a variant of launching stimuli in which A could move with uniformly accelerated or decelerated motion (Experiment 2), non-launching stimuli that elicited a causal impression (Experiment 3), and stimuli showing a three-object launching event (Experiment 4). Main results showed that the judged speed of B was systematically biased towards the speed of A, and moreover that the judged speed of B depended on the average speed of A, rather than on the speed of A at the moment of collision as it would be predicted by Newtonian mechanics. The results are consistent with the hypothesis that internal representations of causal events based on property transmission (for instance, impetus) can affect judgments of the low-level properties of causal scenarios
Launch effect: is the radius of action a function of the time?
No full textIn the launch effect studied by Michotte [1963 The Perception of Causality (London: Methuen)] the radius of action is a critical aspect in the perception of causality: after the contact, the second moving object, from a certain distance on, seems to move autonomously. According to Yela (1952 Quarterly Journal of Experimental Psychology 4 139^154) the radius of action is a function of the time. In the present research, we tested this hypothesis. The experimental para- digm of Michotte (1963) was used. In the experiment, the velocity of the second moving object (50, 75, 100 mm s-1) was varied. Two values (0 ms, 30 ms) of the time interval between the moment of contact of the first object and the moment when the latter begins to move were adopted. Observers indicated where the second moving object lost its passivity and started to move autonomously. The results show that the time duration of the radius of action increases with the velocity of the second moving object, whereas the time interval after the contact is not a significant factor. Our findings suggest that the radius of action is a function of the kinetic properties of the event
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