Recent studies for early vision have been reported by using visual search tasks, and most of them have examined the relation between a target and a distractor. However, it is considered that the distractor attribute as a whole might interfares with target search process, when the spatial interaction between distractors (that is, configuration) has regularity. This is a kind of context effects. Two experiments were performed, in which the regularity of distractor configuration and the target embeddedness were manipulated. The comparison between the regular and irregular configurations is performed with a visual search task in which a target arc is searched in distractor straight short lines on an imaginary concentric circles. As the results, in Experiment 1, search reaction times are delayed when the distractor configuration is regular and a target is embedded in distractors. And, in Experiment 2 with salient targets, search reaction time is facilitated when the distractor configuration is regular and a target disrupts the regularity. These results show that visual search process is affected by whole stimulus attribute, like distractor configuration.
The purpose of this study was to investigate the properties of functional visual fields in visual search processing. Subject's task was to search a target among distractors while EOG was recorded. The target was defined by the difference of the orientation of line segments. The eccentricity of the target was an independent variable and RT and the number of saccades during the stimulus presentation were dependent variables. Although the mean RT and the number of saccades increased as a function of the eccentricity, the increment of RT was not linear. The area in which subjects could find a target within one saccade corresponded the changing point of increment of the RT function. The area was thought as the preattentive sampling areas for the goal of a saccade. The RT increased as a function of eccentricity even when no saccade was observed. The results were discussed in terms of the recent theory of visual search and visual attention.
Using a lexical decision task in which one or two primes were followed by a target, three experiments examined semantic priming for parafoveally presented kanji words. The primes and the targets were two-character kanji words or nonwords. The primes presented parafoveally were semantically related or unrelated to the target word. In the first experiment where one prime was presented parafoveally, priming effect was found, that is, the reaction times were faster when the target word was semantically associated with the parafoveal word. In the second and third experiments, two primes were presented foveally and parafoveally. When the foveal prime was a nonword or a word that was unrelated to the target (Experiment 2), priming effect was not found for the parafoveal words. When the foveal prime was a word that was semantically related or unrelated to the target (Experiment 3), again priming effect was not found for the parafoveal words. These results are discussed in relation to the semantic processing of parafoveal kanji words, attention and reading.
Pitch shifts commonly have been measured by binaural matching. From preliminary observations, however, we found that this phenomenon occurred under the condition of monaural successive comparison. We conducted some experiments to inspect this phenomenon quantitatively. In every experiment, we found the shift of PSE (Point of Subjective Equality) away from the frequency of the leading tone. The most remarkable shifts of pitch were found with the leading tone that have the frequency slightly upper or lower than that of standard tone. This tendency is in line with the results obtained by Sakai (1991) which treated the anchoring effect on judgments of tone height. We found that the greatest shift of pitch was caused at 750ms inter stimulus interval (ISI), and that the effect became weaker with increasing ISI. Therefore we think that pitch shift is an example of the perceptual contrast involving shift of adaptation level as observed in many other perceptual modalities
This experiment examined the orientation effects on identification of single kanjis (Chinese characters). Stimulus were shown at various orientations by rotating the single kanjis in the picture plane. The identification task produced a large orientation effect for complex kanjis (of 14-18 strokes) but a small or no orientation effect for simple kanjis (of 2-6 strokes). The results suggest that the processes producing the orientation effects on stimulus identification differ from those on normal-mirror judgement.