Tau effect

Abstract: In 3 experiments, the authors studied the organization of spatiotemporal information in memory. Stimuli consisted of configurations of dots, presented sequentially. The stimuli were either proportional, with interdot distances corresponding to interdot durations, or not proportional, with interdol distances not corresponding to interdot durations. After a learning phase, participants reproduced the spatial (Experiment 1), temporal (Experiment 2), or spatial and temporal (Experiment 3) characteristics of the target 60 times in succession. In the nonproportional conditions, effects of variable interdot durations or distances on the reproduction of, respectively, constant distances (tau effect) or durations (kappa effect) were observed, whereas no such effects were observed when variable distances or durations were to be produced. Tau and kappa effects influenced the accuracy but not the variability of responses. The results are discussed in light of the distinction between properties of the stabilized mental image and the process of stabilization.

Abstract: Recent studies of position-related proprioceptive sense have provided evidence of a nonpreferred left arm advantage in right-handed individuals. The present study sought to determine whether similar asymmetries might exist in "dynamic position" sense. Thirteen healthy, right-handed adults were blindfolded and seated with arms placed on instrumented manipulanda. In Part 1, subjects performed dynamic position matching of 3 target elbow amplitudes determined with the preferred or nonpreferred arm, and then matched during movement of the same or opposite elbow. In Part 2, a similar paradigm was used, but with varying target determination speeds to account for the so called "tau effect." Overall, it was found that errors were smaller when the matching phase involved the nonpreferred arm, especially for larger target amplitudes. This asymmetry was independent of the tau effect and likely reflects specialization of the right hemisphere/left arm for proprioceptive feedback processing that is either position- or dynamic position-related.

Abstract: The tau effect, an effect of temporal intervals on the perception of spatial separation or sensory difference, has been observed in various sense modalities, including pitch bisection judgments in audition. However, systematic studies on the mechanism of the auditory tau effect have been rather scarce. In the present study, experiments were carried out using the AXB method to investigate the auditory tau effect on the pitch perception of pure tones (Experiment 1), the auditory tau effect on perception of the /e/-/i/, /iA/e/, /I/-/i/, and IM-lll continua (Experiment 2), and the kappa effect—an effect of sensory differences on the perception of temporal intervals—on the perception of pure tones and synthetic vowels (Experiment 3). The results demonstrated that the auditory tau effect occurs not only in the pitch perception of pure tones, but also in the phonetic perception of the fU-iil and /iA/I/ continua of synthetic vowels. The reverse pattern of results was obtained in the /e/-/i/ and /iA/e/ continua. The kappa effect was found both in the pitch perception of pure tones and in phonetic judgments of synthetic vowels. These findings suggest that the interaction between temporal interval and pitch (or phonetic) perception can be explained on the basis of the integration of forward and backward context effects, and that the auditory tau and kappa effects occur at an early stage of auditory information processing.

Abstract: The organization of spatio-temporal information in an auditory memory task was studied in two experiments. Stimuli consisted of four different configurations of eight sequentially presented beeps. In two configurations, the stimuli were space-time congruent, with (constant or variable) inter-stimulus distances corresponding to (constant or variable) inter-stimulus time intervals. In the other two configurations, the stimuli were space-time incongruent, with (constant or variable) inter-stimulus distances not corresponding to (variable or constant) inter-stimulus time intervals. After a learning phase consisting of 20 presentations of the target configuration, participants reproduced the spatial (Experiment 1) or temporal (Experiment 2) characteristics of the target 60 times in succession without re-examining the target configuration. Accuracy (with respect to the target) and variability (between responses) were found to evolve independently. In the incongruent space-time conditions, effects of variable inter-stimulus time intervals or distances on the reproduction of, respectively, constant distances (Tau effect) or constant time intervals (Kappa effect) were observed, while the reverse was not the case. Thus, dimensional interference occurred when the dimension to be ignored was variable. The results are discussed in the light of the distinction between properties of the stabilized mental image and the process of stabilization.