A INFLUÊNCIA DOS ATRIBUTOS VISUAIS NO RECONHECIMENTO DE OBJECTOS: UM ESTUDO DE RESPOSTAS ELECTROFISIOLÓGICAS E HEMODINÂMICAS NO CÓRTEX OCCIPITO-TEMPORAL

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Publications

Cortical brain regions associated with color processing: an FMRI study

Publication . Bramão, Inês; Faísca, Luís; Forkstam, Christian; Reis, Alexandra; Petersson, Karl Magnus

To clarify whether the neural pathways concerning color processing are the same for natural objects, for artifacts objects and for non-objects we examined brain responses measured with functional magnetic resonance imaging (FMRI) during a covert naming task including the factors color (color vs. black&white (B&W)) and stimulus type (natural vs. artifacts vs. non-objects). Our results indicate that the superior parietal lobule and precuneus (BA 7) bilaterally, the right hippocampus and the right fusifom gyrus (V4) make part of a network responsible for color processing both for natural objects and artifacts, but not for non-objects. When color objects (both natural and artifacts) were contrasted with color non-objects we observed activations in the right parahippocampal gyrus (BA 35/36), the superior parietal lobule (BA 7) bilaterally, the left inferior middle temporal region (BA 20/21) and the inferior and superior frontal regions (BA 10/11/47). These additional activations s uggest that colored objects recruit brain regions that are related to visual semantic information/retrieval and brain regions related to visuo-spatial processing. Overall, the results suggest that color information is an attribute that can improve object recognition (behavioral results) and activate a specific neural network related to visual semantic information that is more extensive than for B&W objects during object recognition

2010Journal article

Open access

The contribution of color during object recognition: behavioral, electrophysiological and neuroimaging evidence

Publication . Bramão, Inês; Petersson, Karl Magnus

In this thesis, we present six studies that investigated the role of color information during visual object recognition. The interactions between surface color and color knowledge information were investigated in two studies (chapters 2 and 3). In chapters 4 and 5, we present data that identify the visual processing stage at which color information improves color and non-color diagnostic object recognition. In chapter 6, the neural pathways supporting color object recognition were investigated. Additionally, in an attempt to bring some consistency to the literature, we performed a systematic meta-analysis on the effects of color on object recognition in chapter 7. Chapter 2 and 3 provided data suggesting that surface color information is more influential than color knowledge information during object recognition. Chapter 4 and 5 showed that color information improves the recognition of color and non-color diagnostic objects at different stages of visual processing. Although color information is an important cue for both of these types of objects in the early visual processes, it is also important in later stages of visual processing for color diagnostic object recognition. In chapter 6, we observed that colored objects, when compared with black and white objects, activated a more extensive brain network related to visuo-semantic activation and retrieval. Finally, the meta-analysis in chapter 7 conclusively showed a significant effect of color information during object recognition. In summary, the general picture that emerges from this body of work is that color information takes part in object recognition processes at multiple levels of representation.

2011Doctoral thesis

Open access

The influence of color information on the recognition of color diagnostic and noncolor diagnostic objects

Publication . Bramão, Inês; Inácio, Filomena; Faísca, Luís; Reis, Alexandra; Petersson, Karl Magnus

In the present study, the authors explore in detail the level of visual object recognition at which perceptual color information improves the recognition of color diagnostic and noncolor diagnostic objects. To address this issue, 3 object recognition tasks with different cognitive demands were designed: (a) an object verification task; (b) a category verification task; and (c) a name verification task. The authors found that perceptual color information improved color diagnostic object recognition mainly in tasks for which access to the semantic knowledge about the object was necessary to perform the task; that is, in category and name verification. In contrast, the authors found that perceptual color information facilitates noncolor diagnostic object recognition when access to the object's structural description from long-term memory was necessary—that is, object verification. In summary, the present study shows that the role of perceptual color information in object recognition is dependent on color diagnosticity.

2011Journal article

Restricted access