Priming of hand and foot response- is spatial attention to the body site enough?

The purpose of the present study was to test whether we see evidence for body compatibility effects when viewing both familiar and unusual body postures. Specifically, in a task where colour targets have to be discriminated, we tested whether spatial orienting to a body site is sufficient for effects of body compatibility to emerge when viewing a task-irrelevant body or whether effects are dependent on whether or not we are able to adopt the viewed body posture. The results suggest that spatial orienting to a body site is insufficient; rather we argue that it is only postures that are familiar and we are easily able to adopt that can be processed fluently and influence target discrimination. This points to a key contribution of motor representations to body compatibility effects

The nature and origin of categorical colour perception : cross-cultural and interference task approaches

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The nature and origin of categorical colour perception: Cross-cultural and interference task approaches.

The current thesis presents a series of experiments examining the relationship between language and colour cognition. The main focus is on the categorical perception (CP) of colour, the finding that discrimination of colours that straddle a category boundary is more accurate than within category colour discrimination. It has recently been argued that CP is not a perceptual effect, but rather a direct effect of language due to the comparison of stimulus labels (Roberson & Davidoff, 2000). The current thesis tests this account in a series of colour discrimination tasks with verbal and visual interference, a visual search task and a cross-cultural comparison of speakers of languages that make different categorical colour distinctions. The results of the colour discrimination tasks suggest that the effect of verbal interference on CP is dependent on task design. CP was found to survive verbal interference when the type of interference was not predictable, suggesting that the task was open to encoding strategies. CP did not survive when the colour target was presented with incongruent Stroop interference. An account of CP is proposed in which target name generation is necessary for CP. However, incongruent Stroop interference at test stimuli presentation did not selectively affect CP, suggesting that the process leading to CP is more complex than a simple matching-to-labels account would suggest. Target name generation may activate or reinforce a category code, which in turn facilitates cross-category discrimination. However, as evidence for CP was also found in the visual search task - suggesting that CP can be a perceptual effect - the account of CP proposed here may be specific to certain types of tasks only. The possibility that CP is a memory effect due to a shift towards prototype (Huttenlocher, Hedges & Vevea, 2000) was also considered. The findings presented here suggest that CP is dissociated from a shift towards prototype. The cross-cultural comparison of English and Owambo speakers on a triads and a visual search task allowed a further test of the role of language in colour CP. Language effects were found on both tasks, however, the differences were not all predicted by differences in colour naming. The results suggest that the representation of colour may also differ cross-culturally. Overall, the results presented here suggest that colour perception is not independent of colour language

Patterns of fMRI Activity Dissociate Overlapping Functional Brain Areas that Respond to Biological Motion

SummaryAccurate perception of the actions and intentions of other people is essential for successful interactions in a social environment. Several cortical areas that support this process respond selectively in fMRI to static and dynamic displays of human bodies and faces. Here we apply pattern-analysis techniques to arrive at a new understanding of the neural response to biological motion. Functionally defined body-, face-, and motion-selective visual areas all responded significantly to “point-light” human motion. Strikingly, however, only body selectivity was correlated, on a voxel-by-voxel basis, with biological motion selectivity. We conclude that (1) biological motion, through the process of structure-from-motion, engages areas involved in the analysis of the static human form; (2) body-selective regions in posterior fusiform gyrus and posterior inferior temporal sulcus overlap with, but are distinct from, face- and motion-selective regions; (3) the interpretation of region-of-interest findings may be substantially altered when multiple patterns of selectivity are considered

Perceptual shift in bilingualism: brain potentials reveal plasticity in pre-attentive colour perception

The validity of the linguistic relativity principle continues to stimulate vigorous debate and research. The debate has recently shifted from the behavioural investigation arena to a more biologically grounded field, in which tangible physiological evidence for language effects on perception can be obtained. Using brain potentials in a colour oddball detection task with Greek and English speakers, a recent study suggests that language effects may exist at early stages of perceptual integration [Thierry, G., Athanasopoulos, P., Wiggett, A., Dering, B., & Kuipers, J. (2009). Unconscious effects of language-specific terminology on pre-attentive colour perception. Proceedings of the National Academy of Sciences, 106, 4567-4570]. In this paper, we test whether in Greek speakers exposure to a new cultural environment (UK) with contrasting colour terminology from their native language affects early perceptual processing as indexed by an electrophysiological correlate of visual detection of colour luminance. We also report semantic mapping of native colour terms and colour similarity judgements. Results reveal convergence of linguistic descriptions, cognitive processing, and early perception of colour in bilinguals. This result demonstrates for the first time substantial plasticity in early, pre-attentive colour perception and has important implications for the mechanisms that are involved in perceptual changes during the processes of language learning and acculturation

Unconscious effects of language-specific terminology on preattentive color perception

It is now established that native language affects one's perception of the world. However, it is unknown whether this effect is merely driven by conscious, language-based evaluation of the environment or whether it reflects fundamental differences in perceptual processing between individuals speaking different languages. Using brain potentials, we demonstrate that the existence in Greek of 2 color terms—ghalazio and ble—distinguishing light and dark blue leads to greater and faster perceptual discrimination of these colors in native speakers of Greek than in native speakers of English. The visual mismatch negativity, an index of automatic and preattentive change detection, was similar for blue and green deviant stimuli during a color oddball detection task in English participants, but it was significantly larger for blue than green deviant stimuli in native speakers of Greek. These findings establish an implicit effect of language-specific terminology on human color perception

Doing, seeing, or both: Effects of learning condition on subsequent action perception

It has been proposed that common codes for vision and action emerge from associations between an individual's production and simultaneous observation of actions. This typically first-person view of one's own action subsequently transfers to the third-person view when observing another individual. We tested vision–action associations and the transfer from first-person to third-person perspective by comparing novel hand-action sequences that were learned under three conditions: first, by being performed and simultaneously viewed from a first-person perspective; second, by being performed but not seen; and third, by being seen from a first-person view without being executed. We then used functional magnetic resonance imaging (fMRI) to compare the response to these three types of learned action sequences when they were presented from a third-person perspective. Visuomotor areas responded most strongly to sequences that were learned by simultaneously producing and observing the action sequences. We also note an important asymmetry between vision and action: Action sequences learned by performance alone, in the absence of vision, facilitated the emergence of visuomotor responses, whereas action sequences learned by viewing alone had comparably little effect. This dominance of action over vision supports the notion of forward/predictive models of visuomotor systems