Dynamic distortion of the visual field has been shown to affect perceptual judgment of visual dimensions such as size, length, and distance. Here, we report four experiments demonstrating that the different aspects of a triangle differently influence judgments of distance. Specifically, when the base of the triangle faces the centre of the display, participants consistently underestimate and overestimate the distance of a small dot from the unmarked centre of the display relative to conditions in which the vertex of the triangle faces the centre. When the dot is close to the figure, the distance of the dot to the centre is underestimated. Conversely, when the dot is close to the figure, the distance to the centre is overestimated. The effect is replicated when the internal distances are equalized and when ellipses are used instead of triangles. These results support a ripple model of spatial distortion in which local curvature acts to attract or repel objects. In conclusion, we suggest some implications of our findings for theories of perceptual organization.
Visual search is a task often used in the rehabilitation of patients with cortical and non-cortical visual pathologies such as visual field loss. Reduced visual acuity is often comorbid with these disorders, and it remains poorly defined how low visual acuity may affect a patient's ability to recover visual function through visual search training. The two experiments reported here investigated whether induced blurring of vision (from 6/15 to 6/60) in a neurotypical population differentially affected various types of feature search tasks, whether there is a minimal acceptable level of visual acuity required for normal search performance, and whether these factors affected the degree to which participants could improve with training. From the results, it can be seen that reducing visual acuity did reduce search speed, but only for tasks where the target was defined by shape or size (not colour), and only when acuity was worse than 6/15. Furthermore, searching behaviour was seen to improve with training in all three feature search tasks, irrespective of the degree of blurring that was induced. The improvement also generalised to a non-trained search task, indicating that an enhanced search strategy had been developed. These findings have important implications for the use of visual search as a rehabilitation aid for partial visual loss, indicating that individuals with even severe comorbid blurring should still be able to benefit from such training.
The influence of context on facial expression classification is most often investigated using simple cues in static faces portraying basic expressions with a fixed emotional intensity. We examined (1) whether a perceptually rich, dynamic audiovisual context, presented in the form of movie clips (to achieve closer resemblance to real life), affected the subsequent classification of dynamic basic (happy) and non-basic (sarcastic) facial expressions and (2) whether people's susceptibility to contextual cues was related to their ability to classify facial expressions viewed in isolation. Participants classified facial expressions-gradually progressing from neutral to happy/sarcastic in increasing intensity-that followed movie clips. Classification was relatively more accurate and faster when the preceding context predicted the upcoming expression, compared with when the context did not. Speeded classifications suggested that predictive contexts reduced the emotional intensity required to be accurately classified. More importantly, we show for the first time that participants' accuracy in classifying expressions without an informative context correlated with the magnitude of the contextual effects experienced by them-poor classifiers of isolated expressions were more susceptible to a predictive context. Our findings support the emerging view that contextual cues and individual differences must be considered when explaining mechanisms underlying facial expression classification.
The self-face advantage (SFA) is reflected through a faster recognition of a self-face compared with familiar and unfamiliar faces. Nevertheless, as Westerners and East Asians tend to present differences in self-concept styles, it is possible that the SFA is modulated by culture. The present study explored this possibility using a visual search task. British Caucasians and Malaysian Chinese participants were asked to search for frontal view images of self, friend, and unfamiliar faces among an array of unfamiliar faces. Regardless of race, participants were more accurate and faster in searching for the own face and friend's face compared with an unfamiliar face, with no differences in the search between the own and friend's face, and these findings could not be accounted by the cultural differences in self-concept (i.e., operationalised by scores from the Independent and Interdependent Self-Concept Scale and the Horizontal and Vertical Individualism and Collectivism Scale). Altogether our results suggest that culture does not modulate the SFA and that this effect is better explained by a familiar face advantage.
The retrieval of autobiographical memories involves the construction of mental representations of past personal events. Many researchers examining the processes underlying memory retrieval argue that visual imagery plays a fundamental role. Other researchers, however, have argued that working memory is an integral component involved in memory retrieval. The goal of this study was to resolve these conflicting arguments by comparing the relative contributions of visual imagery and working memory during the retrieval of autobiographical memories in a dual-task paradigm. While following a moving dot, viewing a dynamic visual noise (DVN), or viewing a blank screen, 95 participants recalled their memories and subsequently rated them on different memory characteristics. The results suggest that inhibiting visual imagery by having participants view DVN merely delayed memory retrieval but did not affect the phenomenological quality of the memories retrieved. Taxations to the working memory by having participants follow a moving dot, on the contrary, resulted in only longer retrieval latencies and no reductions in the specificity, vividness, or the emotional intensity of the memories retrieved. Whereas the role of visual imagery during retrieval is clear, future studies could further examine the role of working memory during retrieval by administering a task that is less difficult or by recruiting a larger sample than this study. The results of this study seem to suggest that both visual imagery and working memory play a role during the retrieval of autobiographical memory, but more research needs to be conducted to determine their exact roles.