i-Perception

External bilateral symmetry is a biological marker of normal development and is considered a signal of health and attractiveness across species. Because most human interactions are dynamic, it was hypothesized that observers would be able to perceive spatiotemporal symmetry—symmetry in motion—in human point-light walkers. It was also hypothesized that observers would rate symmetrical walkers as healthy and attractive. Symmetrical and asymmetrical figures were presented to adult participants (n = 22) in motion and as static images with motion implied. Static symmetry was readily perceived, and symmetrical figures were judged significantly healthier and more attractive than asymmetrical figures. However, observers were unable to discriminate symmetry in dynamic presentations. These data provide preliminary evidence of a temporal summation window for a dynamic symmetry perception.

In a recent article, N. Bien, S. ten Oever, R. Goebel, and A. T. Sack (2012) used event-related potentials to investigate the consequences of crossmodal correspondences (the “natural” mapping of features, or dimensions, of experience across sensory modalities) on the time course of neural information processing. Then, by selectively lesioning the right intraparietal cortex using transcranial magnetic stimulation, these researchers went on to demonstrate (for the first time) that it is possible to temporarily eliminate the effect of crossmodal congruency on multisensory integration (specifically on the spatial ventriloquism effect). These results are especially exciting given the possibility that the cognitive neuroscience methodology utilized by Bien et al. (2012) holds for dissociating between putatively different kinds of crossmodal correspondence in future research.

Over the last decade, television screens and display monitors have increased in size considerably, but has this improved our televisual experience? Our working hypothesis was that the audiences adopt a general strategy that “bigger is better.” However, as our visual perceptions do not tap directly into basic retinal image properties such as retinal image size (C. A. Burbeck, 1987), we wondered whether object size itself might be an important factor. To test this, we needed a task that would tap into the subjective experiences of participants watching a movie on different-sized displays with the same retinal subtense. Our participants used a line bisection task to self-report their level of “presence” (i.e., their involvement with the movie) at several target locations that were probed in a 45-min section of the movie “The Good, The Bad, and The Ugly.” Measures of pupil dilation and reaction time to the probes were also obtained. In Experiment 1, we found that subjective ratings of presence increased with physical screen size, supporting our hypothesis. Face scenes also produced higher presence scores than landscape scenes for both screen sizes. In Experiment 2, reaction time and pupil dilation results showed the same trends as the presence ratings and pupil dilation correlated with presence ratings, providing some validation of the method. Overall, the results suggest that real-time measures of subjective presence might be a valuable tool for measuring audience experience for different types of (i) display and (ii) audiovisual material.

Eye movements are strongly influenced by the task given to an observer. The immediacy of such eye movements, which are difficult to control consciously, offers the potential to explore highly variable subjective evaluations, such as aesthetic preference, with reliable objective measures. We presented a variety of images in sets of 2, 4, or 8 items for different durations and analyzed oculomotor statistics such as cumulative fixation duration, refixations, and the sequence of fixations while participants searched for their preferred image, after which participants indicated their preference using a button press. The total amount of time spent looking at any image correlates with selection preference and does so increasingly well with longer presentation duration. For short presentations, the first and last fixations correlate better with image preference. All response measures become increasingly variable as the number and complexity of presented images are increased. A weighted combination of these measures can significantly improve the correlation with preference, suggesting a “signature” which could be used as a reliable indicator for task-free subjective evaluation of stimuli in visual psychophysics. Its role as an improved fitness function in visually driven evolutionary algorithms is discussed.

Crowding is related to an integration of feature signals over an inappropriately large area in the visual periphery. The rules of this integration are still not well understood. This study attempts to understand how the orientation signals from the target and flankers are combined. A target Gabor, together with 2, 4, or 6 flanking Gabors, was briefly presented in a peripheral location (4° eccentricity). The observer's task was to identify the orientation of the target (eight-alternative forced-choice). Performance was found to be nonmonotonically dependent on the target–flanker orientation difference (a drop at intermediate differences). For small target–flanker differences, a strong assimilation bias was observed. An effect of the number of flankers was found for heterogeneous flankers only. It appears that different rules of integration are used, dependent on some salient aspects (target pop-out, homogeneity–heterogeneity) of the stimulus pattern. The strategy of combining simple rules may be explained by the goal of the visual system to encode potentially important aspects of a stimulus with limited processing resources and using statistical regularities of the natural visual environment.

The i-Perception special issue Art & Perception is based on the Art & Perception Conference 2010 in Brussels. Our vision with this conference was to bring together artists and vision scientists from different backgrounds to exchange views and state-of-the-art knowledge on art perception and aesthetics. The complexity of the experience of art and of aesthetic phenomena, in general, calls for specific research approaches, for which interdisciplinarity seems to be key. Following this logic, the special issue Art & Perception contains contributions by artists and vision scientists with different methodological approaches. The contributions span a wide range of topics, but are all centred around two questions: How can one understand art perception and aesthetics from a psychological point of view, and how is this reflected in art itself?

This study tested the perceptual learning theory of size constancy development, which proposes that children younger than 9 years are relatively insensitive to monocular cues for distance and size, and that developmental changes in far-distance size estimation result from increasing sensitivity to these cues. This theory predicts that before 10 years, children will make less accurate size judgments at far distances under monocular than under binocular viewing conditions. Five age groups were tested: 5–6, 7–8, 9–10, 19–28, and 50+ years. Participants judged the size of a standard disc, from viewing distances of 6.1 and 61 m, by pointing at 1 of 9 nearby comparison discs. Testing was conducted under both monocular and binocular viewing conditions. Five- to 6-year-olds underestimated object size at the far distance, 7- to 8-, 9- to 10-year-olds, and older adults made size estimates that were close to accurate, and the young adults significantly overestimated size. At the near distance, all age groups underestimated size and no age differences were found. Contrary to predictions from the perceptual learning theory, viewing condition had no significant effect on size estimates.

Human observers group local shading patterns into global super-patterns that appear to be illuminated in some unitary fashion. Many years ago, this was noticed for the case of uniform, unidirectional illumination. Recently, we found that it also applies to convergent and divergent illumination flows, but that human observers are blind to rotational light flow patterns (in the sense of being unable to group the local shading patterns). We now report that human observers are also blind to deformation patterns. This is perhaps interesting because convergent, divergent, rotational, and deformation patterns all occur in natural light fields. This is an idiosyncrasy of the human visual system, on par with the fact that visual awareness fails to present the observer with saddle shapes.

In distinguishing individual shapes (defined by their contours), older children (6.5 years of age on average) performed better than younger children (4 years of age on average), and, although the task did not involve any categorization or generalization, the error pattern was qualitatively affected by shape differences that are generally common distinctions between objects belonging to different categories. The influence of these shape differences was also observed for unfamiliar shapes, demonstrating that the influence of categorization experience was not modulated by the retrieval of shape features from known categories but rather related to a different perception of shape by age. The results suggest a direct influence of categorization experience on more abstract shape processing. When children were distinguishing shapes, new words were paired with the target shapes, and in 2 additional tasks, the acquired name–shape associations were tested. The younger age group was able to remember more words correctly.