A neural model is developed to explain how humans can approach a goal object on foot while steering around obstacles to avoid collisions in a cluttered environment. The model uses optic flow from a 3-dimensional virtual reality environment to determine the position of objects on the basis of motion discontinuities and computes heading direction,…

The mechanism underlying the reaction time (RT2) slowing to the 2nd of 2 successively presented stimuli (S1 and S2) in the psychological refractory period paradigm was investigated. Stimulus onset synchrony (SOA) between S1 and S2, contrast of S2, and Task 2 set-level compatibility was manipulated. Specifically, the authors used a…

Theories of agency--the feeling of being in control of one's actions and their effects--emphasize either perceptual or cognitive aspects. This study addresses both aspects simultaneously in a finger-tapping paradigm. The tasks required participants to detect when synchronization of their taps with computer-controlled tones changed to…

Multiple sense modalities can be stimulated conjointly by a physically complex item, such as a predator, and also by a physically solitary stimulus that acts on multiple receptor classes. As a prime example of this latter group, l-menthol from mint stimulates taste, smell, and several somatosensory submodalities. In 6 experiments that used a…

Investigations of the relation between judged length and measured length have concentrated on determining the form of the psychophysical function. The process by which the observer arrives at his judgment has not been described. An exploratory experiment was carried out in an attempt to identify the process. (Author)

Research has suggested that perception and action are independent (see M. A. Goodale & A. Haffenden, 1998). The authors used the Ebbinghaus illusion to test this hypothesis in 2 experiments. Verbal reports of perceived size were compared with maximum grip aperture during grasping (Experiment 1) and manual reports of perceived size (Experiment 2).…