Hemispheric Asymmetries Of Temporal Perceptual Thresholds And A New Mensuration Of Thresholds

Many researches on the factors influencing temporal perceptual threshold have limitations on three facets. First, the focuses of these researches have got more into the effects of outer environment or stimuli attribute on temporal perceptual threshold than the cerebral processing characteristics of temporal information. Second, the differences of operational definition of thresholds and experimental conditions used in these researches result in different outcomes and terms, which confines comparability among these researches. Three, there are methodological disadvantages too in the threshold measurement by Classical Psychophysics Method and classical conception of threshold at the bottom of this method used in these researches.This paper, including two studies, employed Divided visual field technique to examine the differences of temporal perceptual thresholds between two cerebral hemispheres and among three kinds of responding models or judgment criteria in the first study. The second study tried to use the method of multidimensional fuzzy assessment, which based on the Fuzzy Set definition of threshold, to evaluate temporal perceptual threshold. The results showed that:(l)There are differences among the temporal perceptual threshold for three kinds of responding models. The factor of judgment criteria also has a significant interaction effect with the factor of stimuli display position (left and right visual field). The simultaneity threshold, which is about 34ms on RH-LVF and 15ms on LH-RVF, is lower than the duration threshold, which is about 145ms on RH-LVF and 147ms on LH-RVF, and the highest one, order threshold, is about 223ms on RH-LVF and 186ms on LH-RVF. The difference between two visual fields is significant on all but the duration threshold. The advantages of right toleft visual field and simultaneity, order to duration judgment were demonstrated by theanalysis of Standard Deviation of responses. The latter have larger SD. A ratio like Weber's Law was found among the variation of different temporal perception thresholds by analyzing their Coefficients of Variance.(2)The hemispheric asymmetry for the temporal perceptual threshold was revealed. The left-hemisphere (right visual field, LH-RVF) is superior on the processing of temporal information to the right-hemisphere (left visual field, RH-LVF) and have lower temporal perceptual thresholds.(3)The method of multidimensional fuzzy assessment was used to measure the succession threshold of temporal perception. But it was showed that the result did not confirm the hemispheric asymmetry for the temporal perceptual threshold. Also, the associations between succession threshold and duration threshold or order threshold in the first study were still not certain. The result here, however, is closer to duration threshold ,which located in the middle, than order threshold numerically.(4) To some extent, the reliability of the method of multidimensional fuzzy assessment was confirmed by the test of its internal consistency. The validity, however, was lack of strong evidences. It seems that this kind of method is not fit enough for the experiments involving fine processing of temporal information.