Attending to threat: Race-based patterns of selective attention

The present research investigated the extent to which the stereotype that young Black men are threatening and dangerous has become so robust and ingrained in the collective American unconscious that Black men now capture attention, much like evolved threats such as spiders and snakes. Specifically, using a dot-probe detection paradigm, White participants revealed biased attention toward Black faces relative to White faces (Study 1). Because the faces were presented only briefly (30-ms), the bias is thought to reflect the early engagement of attention. The attentional bias was eliminated, however, when the faces displayed averted eye-gaze (Study 2). That is, when the threat communicated by the Black faces was attenuated by a relevant, competing socio-emotional cue—in this case, averted eye-gaze—they no longer captured perceivers’ attention. Broader implications for social cognition, as well as public policies that reify these prevailing perceptions of young Black men are discussed.     

Development and Validation of the Clutter Image Rating

Few instruments are available to assess compulsive hoarding and severity of clutter. Accuracy of assessment is important to understanding the clinical significance of the problem. To overcome problems associated with over- and under-reporting of hoarding symptoms, the clutter image rating (CIR) was developed. This pictorial scale contains nine equidistant photographs of severity of clutter representing each of three main rooms of most people’s homes: living room, kitchen, and bedroom. The psychometric properties of this measure were examined in two studies. Internal consistency, test–retest, and interobserver reliabilities were good and convergent validity with other questionnaire and interview measures was also good. The CIR correlated more strongly with measures of clutter than with other hoarding and psychopathology scales. The CIR’s very brief pictorial assessment method makes it useful in clinical and treatment contexts for measuring the clutter dimension of compulsive hoarding. The Clutter Image Rating (CIR) is available in conjunction with the following publication: Steketee, G., & Frost, R.O. (2007). Treatment of compulsive hoarding. New York: Oxford University Press at .     

Visual categorization of natural stimuli by domestic dogs

One of the fundamental issues in the study of animal cognition concerns categorization. Although domestic dogs (Canis familiaris) are on the brink to become one of the model animals in animal psychology, their categorization abilities are unknown. This is probably largely due to the absence of an adequate method for testing dogs’ ability to discriminate between large sets of pictures in the absence of human cueing. Here we present a computer-automated touch-screen testing procedure, which enabled us to test visual discrimination in dogs while social cueing was ruled out. Using a simultaneous discrimination procedure, we first trained dogs (N = 4) to differentiate between a set of dog pictures (N = 40) and an equally large set of landscape pictures. All subjects learned to discriminate between the two sets and showed successful transfer to novel pictures. Interestingly, presentation of pictures providing contradictive information (novel dog pictures mounted on familiar landscape pictures) did not disrupt performance, which suggests that the dogs made use of a category-based response rule with classification being coupled to category-relevant features (of the dog) rather than to item-specific features (of the background). We conclude that dogs are able to classify photographs of natural stimuli by means of a perceptual response rule using a newly established touch-screen procedure. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Female degus (Octodon degus) monitor their environment while foraging socially

Vigilance or scanning involves interruptions in foraging behavior when individuals lift their heads and conduct visual monitoring of the environment. Theoretical considerations assume that foraging with the "head down", and scanning ("head up") are mutually exclusive activities, such that foraging precludes vigilance. We tested this generalization in a socially foraging, small mammal model, the diurnal Chilean degu (Octodon degus). We studied spontaneous bouts of scanning of captive degus when foraging in pairs of female sibs and non-sibs. We examined the extent to which foraging (head down postures) and scanning (head up postures) were mutually exclusive in subjects exposed to none, partial, and complete lateral visual obstruction of their partners. In addition, we monitored the orientation of their bodies to examine the target of attention while foraging and scanning. Lastly, we examined the temporal occurrence of scanning events to assess the extent of scanning coordination, and whether this coordination is kin-biased. Visual obstruction had a significant influence on degu vigilance. Focal degus increased their quadrupedal and semi-erect scanning when foraging under a partially obstructed view of their partners. Degus oriented their bodies toward partners when foraging and scanning. Despite this, degus did not coordinate scanning bouts; instead, they scanned independently from one another. Relatedness among cage mates did not influence any aspect of degu behavior. Contrary to theoretical expectations, these results indicate that foraging and vigilance are not mutually exclusive, and that kinship per se does not influence scanning behavior and coordination.     

Human and machine perception of biological motion

More than 30 years ago, Johansson was the first to show that humans are capable of recovering information about the identity and activity of animate creatures rapidly and reliably from very sparse visual inputs – the phenomenon of biological motion. He filmed human actors in a dark setting with just a few strategic points on the body marked by lights – so-called moving light displays (MLDs). Subjects viewing the MLDs reported a vivid impression of moving human forms, and were even able to tell the activity in which the perceived humans were engaged. Subsequently, the phenomenon has been widely studied and many attempts have been made to model and to understand it. Typical questions that arise are: How precisely is the sparse low-level information integrated over space and time to produce the global percept, and how important is world knowledge (e.g., about animal form, locomotion, gravity, etc.)? In an attempt to answer such questions, we have implemented a machine-perception model of biological motion. If the computational model can replicate human data then it might offer clues as to how humans achieve the task. In particular, if it can do so with no or minimal world knowledge then this knowledge cannot be essential to the perception of biological motion. To provide human data for training and against which to assess the model, an extensive psychophysical experiment was undertaken in which 93 subjects were shown 12 categories of MLDs (e.g., normal, walking backwards, inverted, random dots, etc.) and were asked to indicate the presence or absence of natural human motion. Machine perception models were then trained on normal sequences as positive data and random sequences as negative data. Two models were used: a k-nearest neighbour (k-NN) classifier as an exemplar of ‘lazy’ learning and a back-propagation neural network as an exemplar of ‘eager’ learning. We find that the k-NN classifier is better able to model the human data but it still fails to represent aspects of knowledge about body shape (especially how relative joint positions change under rotation) that appear to be important to human judgements.     

Temporal resolution of figures and grounds

Recent studies have demonstrated that establishing figure–ground organization influences other perceptual processes. Specifically, figures undergo perceptual processing earlier than ground regions (Lester, Hecht, & Vecera, 2009), and they are processed for longer durations relative to ground regions (Hecht & Vecera, 2011). One potential consequence of figures' extended processing is degraded temporal resolution compared to ground regions. To test this hypothesis, observers completed a modified flicker-fusion task while viewing either displays that contained well-defined figures and grounds or displays that were ambiguous. As evidenced by increased sensitivity for flickering targets on the ground regions, the current results support the claim that figures have poorer temporal resolution than ground regions.     

Audiovisual beat induction in complex auditory rhythms: Point-light figure movement as an effective visual beat

This study investigated whether explicit beat induction in the auditory, visual, and audiovisual (bimodal) modalities aided the perception of weakly metrical auditory rhythms, and whether it reinforced attentional entrainment to the beat of these rhythms. The visual beat-inducer was a periodically bouncing point-light figure, which aimed to examine whether an observed rhythmic human movement could induce a beat that would influence auditory rhythm perception. In two tasks, participants listened to three repetitions of an auditory rhythm that were preceded and accompanied by (1) an auditory beat, (2) a bouncing point-light figure, (3) a combination of (1) and (2) synchronously, or (4) a combination of (1) and (2), with the figure moving in anti-phase to the auditory beat. Participants reproduced the auditory rhythm subsequently (Experiment 1), or detected a possible temporal change in the third repetition (Experiment 2). While an explicit beat did not improve rhythm reproduction, possibly due to the syncopated rhythms when a beat was imposed, bimodal beat induction yielded greater sensitivity to a temporal deviant in on-beat than in off-beat positions. Moreover, the beat phase of the figure movement determined where on-beat accents were perceived during bimodal induction. Results are discussed with regard to constrained beat induction in complex auditory rhythms, visual modulation of auditory beat perception, and possible mechanisms underlying the preferred visual beat consisting of rhythmic human motions.     

Parallel averaging of size is possible but range-limited: A reply to Marchant,Simons, and De Fockert

In their recent paper, Marchant, Simons, and De Fockert (2013) claimed that the ability to average between multiple items of different sizes is limited by small samples of arbitrarily attended members of a set. This claim is based on a finding that observers are good at representing the average when an ensemble includes only two sizes distributed among all items (regular sets), but their performance gets worse when the number of sizes increases with the number of items (irregular sets). We argue that an important factor not considered by Marchant et al. (2013) is the range of size variation that was much bigger in their irregular sets. We manipulated this factor across our experiments and found almost the same efficiency of averaging for both regular and irregular sets when the range was stabilized. Moreover, highly regular sets consisting only of small and large items (two-peaks distributions) were averaged with greater error than sets with small, large, and intermediate items, suggesting a segmentation threshold determining whether all variable items are perceived as a single ensemble or distinct subsets. Our results demonstrate that averaging can actually be parallel but the visual system has some difficulties with it when some items differ too much from others.     

Right hemisphere specialization for color detection

Three experiments were carried out to investigate hemispheric asymmetry in color processing among normal participants. In Experiment 1, it was shown that the reaction times (RTs) of the dominant and non-dominant hands assessed using a visual target presented at the central visual field, were not significantly different. In Experiment 2, RTs of ipsilateral hands to lateralized chromatic stimuli revealed that the processing time was 17 ms shorter in the right hemisphere (RH) than that in the left hemisphere among the right-handed participants, whereas no significant difference was found among the left-handed participants. On the other hand, RTs to lateralized achromatic stimuli showed no such asymmetry among both the right- and left-handed participants (Experiment 3). These findings strongly suggest RH superiority for detection of color among right-handed individuals.     

Portraits as displays

Cynthia Freeland’s investigation of four kinds of ‘fidelity’ in portraiture is cut across by more general philosophical concerns. One is about what might be called the expression of persons--the persons or ‘inner selves’ of portrait subjects and of portrait artist: whether either is possible across each of the four kinds of fidelity, and whether these two kinds of expression are in tension. More fundamental is the problem of telling how self-expression is at all possible in any of these forms. Finally, she wonders how photography affects all these questions. This comment addresses portraiture not so much in terms of the four fidelities, but with another quartet of concepts: four ordinary types of ‘display’, in terms of which we see how artists’ self-expression is possible in all these forms, also including photography. Its key idea is that portraits are displays simply by being pictures or sculptures, which are kinds of artifacts, hence things that we perceive as having intentional affordance: that is, as being intentionally made ‘for’ something.