Now you see it,now you don't: The context dependent nature of category-effects in visual object recognition

In two experiments, we test predictions regarding processing advantages/disadvantages for natural objects and artefacts in visual object recognition. Varying three important parameters—degree of perceptual differentiation, stimulus format, and stimulus exposure duration—we show how different category-effects can be provoked in normal subjects on the same task. We interpret the results in light of the Pre-semantic Account of Category Effects (PACE; Gerlach, 2009), and conclude that category-effects do not reflect absolute processing differences between categories. Rather, category-effects are products of common operations which are differentially affected by the structural similarity among objects (with natural objects being more structurally similar than artefacts). The potentially most important aspect of the present study is the demonstration that category-effects are very context dependent; an aspect which has been neglected in earlier literature on category-specificity. PACE provides a useful framework in this respect, as it specifies how category-effects are influenced by changes in task and stimulus characteristics.     

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.     

Perceptual visual grouping under inattention: electrophysiological functional imaging

Two types of perceptual visual grouping, differing in complexity of shape formation, were examined under inattention. Fourteen participants performed a similarity judgment task concerning two successive briefly presented central targets surrounded by task-irrelevant simple and complex grouping patterns. Event-related potentials (ERPs) were recorded from 22 scalp electrodes and source current density estimations were conducted for the net response to the task-irrelevant background patterns, using low-resolution electromagnetic tomography (LORETA). Although participants’ subjective reports indicated that neither type of organization induced awareness, electrophysiological results showed they both evoked significant activation in occipital, parieto-temporal and frontal brain areas. Behavioral results demonstrated that only grouping of the simple pattern arose under inattention. In contrast to the complex pattern, the processing of the simple pattern was associated with an initially longer latency and higher activation beginning at 130 ms. These results support the distinction of grouping patterns differing in complexity of shape formation.     

Superordinate shape classification using natural shape statistics

This paper investigates the classification of shapes into broad natural categories such as animal or leaf. We asked whether such coarse classifications can be achieved by a simple statistical classification of the shape skeleton. We surveyed databases of natural shapes, extracting shape skeletons and tabulating their parameters within each class, seeking shape statistics that effectively discriminated the classes. We conducted two experiments in which human subjects were asked to classify novel shapes into the same natural classes. We compared subjects’ classifications to those of a naive Bayesian classifier based on the natural shape statistics, and found good agreement. We conclude that human superordinate shape classifications can be well understood as involving a simple statistical classification of the shape skeleton that has been “tuned” to the natural statistics of shape.     

THE CONSEQUENCES OF METAPHYSICS: OR,CAN CHARLES PEIRCE'S CONTINUITY THEORY MODEL STUART KAUFFMAN'S BIOLOGY?

At the heart of the most radical proposals in Stuart Kauffman's Investigations is his attempt to show that we find in evolutionary biology some configuration spaces—the sets of possible developments for any given system—that (unlike those in traditional physics of Newtonian, relativistic, and quantum stripes) cannot be completely described in advance. We bring Charles Peirce's work on the philosophy of continuity to bear on the problem and discover, first, that Kauffman's arguments do not succeed; second, that Peirce's metaphysics provide new and sounder arguments for the same propositions; third, that Peirce's rigorous but nonstandard treatment of mathematical continuity shows great promise for modeling the unpredictability and growth we find in evolutionary biology; fourth, that it also strengthens a development only hinted at by biologists thus far—the inevitable involvement of the observer's mind in constituting the objects of science. We close with a logical argument for the surprising relevance of metaphysical hypotheses in the natural sciences and with suggestions for future work that will connect these questions to what Kauffman terms the “narrative stance” in biology.     

Body-related film clip triggers desire to binge in women with binge eating disorder

Previous research suggests that excessive influence of shape or weight concern on self-evaluation is strongly associated with psychological functioning in women with binge eating disorder (BED). However, little is known so far about its direct influence on binge episodes. In an experimental study, 27 women with BED (DSM-IV) and 25 overweight healthy controls watched a body-related film clip. Ratings of the desire to binge and mood were assessed prior to and at the end of the film clip. Additionally, measures of heart rate, finger pulse and electrodermal activity were obtained. Main results revealed a significant increase in the desire to binge, sadness and anxiety, as well as a significant increase in non-specific skin conductance fluctuation on the body-related clip in the group of BED only. The results underline the importance of shape and weight concerns in BED.     

The Shape Bias is Affected by Differing Similarity Among Objects

Previous research has demonstrated that visual properties of objects can affect shape-based categorization in a novel-name extension task; however, we still do not know how a relationship between visual properties of objects affects judgments in a novel-name extension task. We examined effects of increased visual similarity among the target and test objects in a shape bias task in young children and adults. Experiment 1 assessed college students with sets of objects whose similarity between target and test objects was either low or high similarity. Adults preferred shape when the similarity among objects was minimized. Experiment 2 tested 24-month olds in their use of the shape bias using the Intermodal Preferential Looking Paradigm. Children showed a shape bias only with items whose similarity to each other was low. These findings suggest that the visual properties of objects affect shape bias performance.     

The contribution of shape and surface information in the other-race face effect

Faces from another race are generally more difficult to recognize than faces from one's own race. However, faces provide multiple cues for recognition and it remains unknown what are the relative contribution of these cues to this “other-race effect”. In the current study, we used three-dimensional laser-scanned head models which allowed us to independently manipulate two prominent cues for face recognition: the facial shape morphology and the facial surface properties (texture and colour). In Experiment 1, Asian and Caucasian participants implicitly learned a set of Asian and Caucasian faces that had both shape and surface cues to facial identity. Their recognition of these encoded faces was then tested in an old/new recognition task. For these face stimuli, we found a robust other-race effect: Both groups were more accurate at recognizing own-race than other-race faces. Having established the other-race effect, in Experiment 2 we provided only shape cues for recognition and in Experiment 3 we provided only surface cues for recognition. Caucasian participants continued to show the other-race effect when only shape information was available, whereas Asian participants showed no effect. When only surface information was available, there was a weak pattern for the other-race effect in Asians. Performance was poor in this latter experiment, so this pattern needs to be interpreted with caution. Overall, these findings suggest that Asian and Caucasian participants rely differently on shape and surface cues to recognize own-race faces, and that they continue to use the same cues for other-race faces, which may be suboptimal for these faces.     

A Cross-Cultural Exploration: Body Image in Older Black and White Women in the Workplace

This study investigated body image attitudes in a non-clinical sample of black and white older professional women in the workplace in South Africa. Participants were 125 professional women (white woman n=76 and black women n = 49). They completed the shortened version of the Body Shape Questionnaire (BSQ) (Cooper, Taylor, Cooper & Fairburn, 1987). The BSQ is a self-report instrument that measures weight and shape concerns. One-way analysis of variance (ANOVA) and t-tests for independent samples were used to determine the univariate relationships between variables. Following this, a two-way analysis of Variance (ANOVA) was conducted to explore the interaction between ethnicity and BMI. The results indicate that Body Mass Index (BMI) and ethnicity are significantly and independently related to the body shape image. Women with higher BMI scores tended to have more concern about their bodies. Black women with higher BMI scores had more concerns than their white colleagues.     

A computational account of the development of the generalization of shape information

Abecassis, Sera, Yonas, and Schwade (2001) showed that young children represent shapes more metrically, and perhaps more holistically, than do older children and adults. How does a child transition from representing objects and events as undifferentiated wholes to representing them explicitly in terms of their attributes? According to RBC (Recognition‐by‐Components theory; Biederman, 1987 ), objects are represented as collections of categorical geometric parts (“geons”) in particular categorical spatial relations. We propose that the transition from holistic to more categorical visual shape processing is a function of the development of geon‐like representations via a process of progressive intersection discovery. We present an account of this transition in terms of DORA ( Doumas, Hummel, & Sandhofer, 2008 ), a model of the discovery of relational concepts. We demonstrate that DORA can learn representations of single geons by comparing objects composed of multiple geons. In addition, as DORA is learning it follows the same performance trajectory as children, originally generalizing shape more metrically/holistically and eventually generalizing categorically.