[Show abstract][Hide abstract] ABSTRACT: We investigated distractor processing in a dual-target rapid serial visual presentation (RSVP) task containing familiar objects, by measuring repetition priming from a priming distractor (PD) to Target 2 (T2). Priming from a visually identical PD was contrasted with priming from a PD in a different orientation from T2. We also tested the effect of attention on distractor processing, by placing the PD either within or outside the attentional blink (AB). PDs outside the AB induced positive priming when they were in a different orientation to T2 and no priming, or negative priming, when they were perceptually identical to T2. PDs within the AB induced positive priming regardless of orientation. These findings demonstrate (1) that distractors are processed at multiple levels of representation; (2) that the view-specific representations of distractors are actively suppressed during RSVP; and (3) that this suppression fails in the absence of attention.
Preview · Article · Dec 2010 · Journal of Experimental Psychology Human Perception & Performance
[Show abstract][Hide abstract] ABSTRACT: We investigated the role played by the right parietal lobe in object identification and the ability to interpret object orientation, using transcranial magnetic stimulation (TMS) to momentarily interfere with ongoing cortical activity. Short trains of TMS pulses (12 Hz) were applied to a site overlying the right intraparietal sulcus/inferior parietal lobe while subjects performed either object identification tasks (i.e., picture-word verification and categorizing objects as natural or manufactured) or object orientation judgment tasks (i.e., picture-arrow verification and deciding whether an object was rotated clockwise or counterclockwise). Across different tasks, right parietal TMS impaired orientation judgments, but facilitated object identification, compared to TMS applied to a brain vertex control site. These complementary findings demonstrate that the right parietal lobe--a region belonging to the dorsal visual stream--is critical for processing the spatial attributes of objects, but not their identity. The observed improvement in object recognition, however, suggests an indirect role for the right parietal lobe in object recognition. We propose that this involves the creation of a spatial reference frame for the object, which allows interaction with the object and the individuation of specific viewing instances.
Full-text · Article · Jun 2008 · Journal of Cognitive Neuroscience
[Show abstract][Hide abstract] ABSTRACT: An ongoing debate in the object recognition literature centers on whether the shape representations used in recognition are coded in an orientation-dependent or orientation-invariant manner. In this study, we asked whether the nature of the object representation (orientation-dependent vs orientation-invariant) depends on the information-processing stages tapped by the task.
We employed a repetition priming paradigm in which briefly presented masked objects (primes) were followed by an upright target object which had to be named as rapidly as possible. The primes were presented for variable durations (ranging from 16 to 350 ms) and in various image-plane orientations (from 0 degrees to 180 degrees, in 30 degrees steps). Significant priming was obtained for prime durations above 70 ms, but not for prime durations of 16 ms and 47 ms, and did not vary as a function of prime orientation. In contrast, naming the same objects that served as primes resulted in orientation-dependent reaction time costs.
These results suggest that initial processing of object identity is mediated by orientation-independent information and that orientation costs in performance arise when objects are consolidated in visual short-term memory in order to be reported.