Biomedical subjects

E Gyulai

Publications and source records attributed to E Gyulai.

8 recordsLinked to original sources

PubMed1997

The "jump" and "release" effects: some observations on the perception of causality.

Two experiments studied the "release" and "jump" effects. Suppose that--on a homogeneous background--a single object moving on a straight trajectory has a constant physical velocity along all its path except in the middle where this velocity is higher or lower for a short time. The release effect occurs when this velocity is lower and the jump effect when it is higher. In the release effect, the object appears to be released from something that held it back. In the jump effect, the object appears to make a jump forward. In line with Premack's 1990 view, these effects suggest a reclassification of causal phenomena in terms of the perceived origin of the change in movement. This origin is perceived as external in Michotte's launching effect and as both internal and external in the release effect and as internal in the jump effect.

Color Perception↗

PubMed1996

The "jump" effect.

The jump effect occurs when an object, for example, a small square, moves on a homogeneous background at a constant velocity along its path except for a short section wherein the velocity suddenly changes to a higher value. In correspondence with this increase, observers may report that the object appears to jump. The experiments reported here explored the velocity conditions which determine the occurrence of this perceptual jump. A difference of at least 15 cm/sec. between the two velocities of the object was necessary for the effect to occur with probability 0.5. With slightly lower frequency, the effect also occurred when the object increased its velocity to a higher constant value in a short part of its path and then stopped. For the phenomenal jump to occur in all the different conditions used, there had to be an optimal length of the path in which the object increased its velocity. Finally, both velocities, before and after this increase, influenced the jump, although each with different weight.

Acceleration↗

PubMed1990

Perceptual inequality between two physically equal constant velocities.

When an object moves with an equal constant velocity before and after passing through a tunnel (or before and after a sudden acceleration--or deceleration--in the central part of its trajectory), the two velocities (the one preceding and the one following the tunnel or the sudden acceleration or deceleration) are perceived as different even if actually physically equal. Four experiments were carried out to underestimation of the second velocity (i.e., the one following the tunnel) when the first one (i.e., the one preceding the tunnel) is low, and an overestimation of the second one when the values of the first velocity are higher. An interpretation of the results is proposed, suggesting that an appearance effect (i.e., an apparent higher velocity at the beginning of the movement) could be for the perceptual inequality between the two physically equal constant velocities.

Attention↗

PubMed1970