Purchase this article with an account.
Jeong Su Keun, Yaoda Xu; Neural representation of targets and distractors during object individuation and identification. Journal of Vision 2010;10(7):180. doi: 10.1167/10.7.180.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Many everyday activities, such as driving on a busy street, require the encoding of multiple distinctive target objects among distractor objects. To explain how multiple visual objects are attended and perceived, the neural object file theory argues that our visual system first selects a fixed number of about four objects from a crowded scene based on their spatial/temporal information (object individuation) and then encodes their details (object identification) (Xu & Chun, 2009, TICS). In particular, while object individuation involves the inferior intra-parietal sulcus (IPS), object identification involves the superior IPS and higher visual areas such as the lateral occipital complex (LOC). Because task irrelevant distractor objects were never present in previous studies, it is unclear how distractor objects are processed and whether they influence the encoding of target objects during object individuation and identification. In the current fMRI study, we asked observers to encode target shapes among distractor shapes, with targets and distractors defined by two different colors. If distractors can be ignored based on their color before objects are individuated and identified, then the presence of distractors should have minimal impact on fMRI responses in the inferior and the superior IPS and the LOC. However, if distractors are automatically individuated or even identified, then neural responses in the relevant brain areas should be modulated accordingly. In a third possibility, if irrelevant information is only encoded when the central processing resources are unfilled as argued by the perceptual load theory, then distractors will be processed under low but not under high target load. Consistent with the perceptual load theory, we found that distractors only affected neural responses under low, but not under high, target load. Moreover, the presence of distractors under low target load had different effects on fMRI responses in the inferior and the superior IPS and the LOC.
This PDF is available to Subscribers Only