Cultural specialization of visual cortex

Cross-cultural comparison of the neural correlates of true and false memory retrieval

Prior work has shown Americans have higher levels of memory specificity than East Asians. Neuroimaging studies have not investigated mechanisms that account for cultural differences at retrieval. In this study, we use fMRI to assess whether mnemonic discrimination, distinguishing novel from previously encountered stimuli, accounts for cultural differences in memory. Fifty-five American and 55 Taiwanese young adults completed an object recognition paradigm testing discrimination of old targets, similar lures and novel foils. Mnemonic discrimination was tested by comparing discrimination of similar lures from studied targets, and results showed the relationship between activity in right fusiform gyrus and behavioural discrimination between target and lure objects differed across cultural groups. Parametric modulation analyses of activity during lure correct rejections also indicated that groups differed in left superior parietal cortex response to variations in lure similarity. Additional analyses of old vs. new activity indicated that Americans and Taiwanese differ in the neural activity supporting general object recognition in the hippocampus, left inferior frontal gyrus and middle frontal gyrus. Results are juxtaposed against comparisons of the regions activated in common across the two cultures. Overall, Americans and Taiwanese differ in the extent to which they recruit visual processing and attention modulating brain regions.

Mapping the neural mechanism that distinguishes between holistic thinking and analytic thinking

Holistic and analytic thinking are two distinct modes of thinking used to interpret the world with relative preferences varying across cultures. While most research on these thinking styles has focused on behavioral and cognitive aspects, a few studies have utilized functional magnetic resonance imaging (fMRI) to explore the correlations between brain metrics and self-reported scale scores. Other fMRI studies used single holistic and analytic thinking tasks. As a single task may involve processing in spurious low-level regions, we used two different holistic and analytic thinking tasks, namely the frame-line task and the triad task, to seek convergent brain regions to distinguish holistic and analytic thinking using multivariate pattern analysis (MVPA). Results showed that brain regions fundamental to distinguish holistic and analytic thinking include the bilateral frontal lobes, bilateral parietal lobes, bilateral precentral and postcentral gyrus, bilateral supplementary motor areas, bilateral fusiform, bilateral insula, bilateral angular gyrus, left cuneus, and precuneus, left olfactory cortex, cingulate gyrus, right caudate and putamen. Our study maps brain regions that distinguish between holistic and analytic thinking and provides a new approach to explore the neural representation of cultural constructs. We provide initial evidence connecting culture-related brain regions with language function to explain the origins of cultural differences in cognitive styles.

Do cultural differences emerge at different levels of representational hierarchy?

In prior research, Eastern and Western culture groups differ in memory specificity for objects. However, these studies used concrete object stimuli, which carry semantic information that may be confounded with culture. Additionally, the perceptual properties of the stimuli were not tightly controlled. Therefore, it cannot be precisely determined whether the observed cross-cultural differences are generalizable across different stimulus types and memory task demands. In prior studies, Americans demonstrated higher memory specificity than East Asians, but this may be due to Americans being more attuned to the low-level features that distinguish studied items from similar lures, rather than general memory differences. To determine whether this pattern of cross-cultural memory differences emerges irrespective of stimulus properties, we tested American and East Asian young adults using a recognition memory task employing abstract stimuli for which attention to conjunctions of features was critical for discrimination. Additionally, in order to more precisely determine the influence of stimulus and task on culture differences, participants also completed a concrete objects memory task identical to the one used in prior research. The results of the abstract objects task mirror the pattern seen in prior studies with concrete objects: Americans showed generally higher levels of recognition memory performance than East Asians for studied abstract items, whether discriminating them from similar or entirely new items. Results from the current concrete object task generally replicated this pattern. This suggests cross-cultural memory differences generalize across stimulus types and task demands, rather than reflecting differential sensitivity to low-level features or higher-level conjunctions.

Functional connectivity with medial temporal regions differs across cultures during post-encoding rest

Connectivity of the brain at rest can reflect individual differences and impact behavioral outcomes, including memory. The present study investigated how culture influences functional connectivity with regions of the medial temporal lobe. In this study, 46 Americans and 59 East Asians completed a resting state scan after encoding pictures of objects. To investigate cross-cultural differences in resting state functional connectivity, left parahippocampal gyrus (anterior and posterior regions) and left hippocampus were selected as seed regions. These regions were selected, because they were previously implicated in a study of cultural differences during the successful encoding of detailed memories. Results revealed that left posterior parahippocampal gyrus had stronger connectivity with temporo-occipital regions for East Asians compared with Americans and stronger connectivity with parieto-occipital regions for Americans compared with East Asians. Left anterior parahippocampal gyrus had stronger connectivity with temporal regions for East Asians than Americans and stronger connectivity with frontal regions for Americans than East Asians. Although connectivity did not relate to memory performance, patterns did relate to cultural values. The degree of independent self-construal and subjective value of tradition were associated with functional connectivity involving left anterior parahippocampal gyrus. Findings are discussed in terms of potential cultural differences in memory consolidation or more general trait or state-based processes, such as holistic versus analytic processing.

Spatial frequency impacts perceptual and attentional ERP components across cultures

Culture impacts visual perception in several ways.To identify stages of perceptual processing that differ between cultures, we usedelectroencephalography measures of perceptual and attentional responses to simple visual stimuli.Gabor patches of higher or lower spatialfrequencywere presented at high contrast to 25 American and 31 East Asian participants while they were watching for the onset of aninfrequent, oddball stimulus. Region of interest and mass univariate analyses assessed how cultural background and stimuli spatial frequency affected the visual evoked response potentials. Across both groups, the Gabor of lower spatial frequency produced stronger evoked response potentials in the anterior N1 and P3 than did the higher frequency Gabor. The mass univariate analyses also revealed effects of spatial frequency, including a frontal negativity around 150 ms and a widespread posterior positivity around 300 ms. The effects of spatial frequency generally differed little across cultures; although there was some evidence for cultural differences in the P3 response to different frequencies at the Pz electrode, this effect did not emerge in the mass univariate analyses. We discuss these results in relation to those from previous studies, and explore the potential advantages of mass univariate analyses for cultural neuroscience.

Cultural Differences in Face Recognition and Potential Underlying Mechanisms

The ability to recognize a face is crucial for the success of social interactions. Understanding the visual processes underlying this ability has been the focus of a long tradition of research. Recent advances in the field have revealed that individuals having different cultural backgrounds differ in the type of visual information they use for face processing. However, the mechanisms that underpin these differences remain unknown. Here, we revisit recent findings highlighting group differences in face processing. Then, we integrate these results in a model of visual categorization developed in the field of psychophysics: the RAP framework. On the basis of this framework, we discuss potential mechanisms, whether face-specific or not, that may underlie cross-cultural differences in face perception.