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Biomedical subjects

S Maedo

Publications and source records attributed to S Maedo.

2 recordsLinked to original sources

[Object-specific priming in apparent motion display].

The perceptual process of an object with multiple features mainly consists of two stages. At first, features are encoded independently at the modular level (feature level). Secondly, they are recombined to build a temporal representation of the object (conjunctive level). Using the apparent motion technique in which stimuli were defined by color and shape, we examined the levels at which the object-specific priming takes place. Although the discrimination of the second stimulus was facilitated when it shared the features with the first stimulus, the priming effects were different according to the number of stimulus items of the first frame. When the first frame contained one stimulus item, the priming benefits were obtained at the both conjunctive and the feature levels. However, the benefit was found only at the feature level when the item number was increased to eight (one of them disappeared in the following frames as the apparent motion stimulus). The roles of modular analysis and attention integration were discussed in terms of the economical validity of feature preservation in object perception.

Adult

[Effects of display and memory load on event-related potentials during a visual search task].

We recorded event-related potentials (ERPs) in nine normal adult subjects to investigate the effects of display load (number of positions to be processed) and memory load (memory set size) on ERPs in visual search tasks. The stimulus consisted of a horizontal array of five different alphabets. In search task, subjects were required to respond only to stimuli containing a target letter. In a simple reaction task, they were required to respond to all the stimuli. The results showed that display load affected N200 and NA deflections recorded at occipital and posterior temporal electrodes, although memory load did not affect them. We also found the different effects of display load and memory load on search-related negativities. That is, in latency, search-related negativities with increasing display load appeared before those with memory load. The difference in topography between display and memory load effects on search-related negativities was not confirmed statistically. The validity of ERPs as indices for the visual and memory search processes was discussed.

Adult