Cross-species differences in color categorization

Berlin and Kay (1969) found systematic restrictions in the color terms of the world’s languages and were inclined to look to the primate visual system for their origin. Because the visual system does not provide adequate neurophysiological discontinuities to supply natural color category boundaries, and because recent evidence points to a linguistic origin (Davidoff, Davies, & Roberson, 1999), a new approach was used to investigate the controversial issue of the origin of color categories. Baboons and humans were given the same task of matching-to-sample colors that crossed the blue/green boundary. The data and consequent modeling were remarkably clear-cut. All human subjects matched our generalization probe stimuli as if to a sharp boundary close to the midpoint between their training items. Despite good color discrimination, none of the baboons showed any inclination to match to a single boundary but rather responded with two boundaries close to the training stimuli. The data give no support to the claim that color categories are explicitly instantiated in the primate color vision system.     

Priming of depth-rotated objects depends on attention and part changes

Three priming experiments investigated the role of attention and view changes when common objects were rotated in depth. Objects were shown in prime-probe trial pairs. Experiment 1 extended findings by Stankiewicz, Hummel, and Cooper (1998) showing that attended objects primed themselves in the same but not in a reflected view, whereas ignored objects only primed themselves in the same view. In Experiment 2, depth-rotations produced changes in the visible part structure between prime and probe view of an object. Priming after depth-rotation was more reduced for attended objects than for ignored objects. Experiment 3 showed that other depth rotations that did not change the perceived part structure revealed a priming pattern similar to that in Experiment 1, with equivalent reduction in priming for attended and ignored objects. These data indicate that recognition of attended objects is mediated by a part-based (analytic) representation together with a view-based (holistic) representation, whereas ignored images are recognized in a strictly view-dependent fashion.     

Color terms and color concepts

In their lead articles, both Kowalski and Zimiles (2006) and O'Hanlon and Roberson (2006) declare a general relation between color term knowledge and the ability to conceptually represent color. Kowalski and Zimiles, in particular, argue for a priority for the conceptual representation in color term acquisition. The complexities of the interaction are taken up in the current commentary, especially with regard to the neuropsychological evidence. Data from aphasic patients also argue for a priority for abstract thought, but nevertheless it may still be that the use of color terms is the only way in which to form color categories even if both linguistic and attentional factors play an important role.     

A cross-cultural study of the representation of shape: Sensitivity to generalized cone dimensions

Many of the phenomena underlying shape recognition can be derived from an assumption that the representation of simple parts can be understood in terms of independent dimensions of generalized cones, e.g., whether the axis of a cylinder is straight or curved or whether the sides are parallel or nonparallel. What enables this sensitivity? One explanation is that the representations derive from our immersion in a manufactured world of simple objects, e.g., a cylinder and a funnel, where these dimensions can be readily discerned independent of other stimulus variations. An alternative explanation is that genetic coding and/or early experience with extended contours—a characteristic of all naturally varying visual worlds—would be sufficient to develop the appropriate representations. The Himba, a seminomadic people in a remote region of Northwestern Namibia with little exposure to regular, simple artifacts, were virtually identical to western observers in representing generalized-cone dimensions of simple shapes independently. Thus immersion in a world of simple, manufactured shapes is not required for the development of a representation that specifies these dimensions independently.     

The Clinical Application of Phantasy Studies

The role of external genital sensory feedback and sex of S and the effects on copulatory behavior were investigated. The prevention of semen plugs and anesthetization of the vagina had no significant effect on the running times of the female or the number of mounts of the male, when compared to a control group. Anesthetization of the penis and prevention of erection significantly reduced the number of mounts made by the male. Short term changes in external genital sensory feedback were found to be one factor affecting copulation; however, nonsexual factors were also suggested as possible determinants and cited as areas of subsequent research.     

Categorical perception of animal patterns

As part of the more general issue of whether culture can affect perception, the present paper addresses the Whorfian question of whether the language available to describe perceptual experience can influence the experience itself. It investigated the effect of vocabulary on perceptual classification by the study of a remote culture (Himba) which possesses a poor colour vocabulary but a rich vocabulary of animal pattern terms. Thus, the present study examined Categorical Perception (CP) with a type of visual stimulus not previously used to assess the effect of labels on perceptual judgments. For the animal patterns, the Whorfian view predicted that it would only be the Himba who showed superiority for cross‐category decisions as only they have the appropriate labels. The Whorfian view was upheld and confirmed previous findings that linked perceptual differences to labelling differences.     

Face familiarity, distinctiveness, and categorical perception

Four experiments with faces support the original interpretation of categorical perception (CP) as only present for familiar categories. Unlike in the results of Levin and Beale (2000), no evidence is found for face identity CP with unfamiliar faces. Novel face identities were shown to be capable of encoding for immediate sorting purposes but the representations utilized do not have the format of perceptual categories. One possibility explored was that a choice of a distinctive face as an end-point in a morphed continuum can spuriously produce effects that resemble CP. Such morphed continua provided unequal psychological responses to equal physical steps though much more so in a better likeness paradigm than for forced-choice recognition. Thus, researchers doing almost the same experiments may produce very different results and come to radically different conclusions.     

Maximizing noise energy for noise-masking studies

Noise-masking experiments are widely used to investigate visual functions. To be useful, noise generally needs to be strong enough to noticeably impair performance, but under some conditions, noise does not impair performance even when its contrast approaches the maximal displayable limit of 100 %. To extend the usefulness of noise-masking paradigms over a wider range of conditions, the present study developed a noise with great masking strength. There are two typical ways of increasing masking strength without exceeding the limited contrast range: use binary noise instead of Gaussian noise or filter out frequencies that are not relevant to the task (i.e., which can be removed without affecting performance). The present study combined these two approaches to further increase masking strength. We show that binarizing the noise after the filtering process substantially increases the energy at frequencies within the pass-band of the filter given equated total contrast ranges. A validation experiment showed that similar performances were obtained using binarized-filtered noise and filtered noise (given equated noise energy at the frequencies within the pass-band) suggesting that the binarization operation, which substantially reduced the contrast range, had no significant impact on performance. We conclude that binarized-filtered noise (and more generally, truncated-filtered noise) can substantially increase the energy of the noise at frequencies within the pass-band. Thus, given a limited contrast range, binarized-filtered noise can display higher energy levels than Gaussian noise and thereby widen the range of conditions over which noise-masking paradigms can be useful.