Audiovisual synchrony and temporal order judgments: effects of experimental method and stimulus type

When an audio-visual event is perceived in the natural environment, a physical delay will always occur between the arrival of the leading visual component and that of the trailing auditory component. This natural timing relationship suggests that the point of subjective simultaneity (PSS) should occur at an auditory delay greater than or equal to 0 msec. A review of the literature suggests that PSS estimates derived from a temporal order judgment (TOJ) task differ from those derived from a synchrony judgment (SJ) task, with (unnatural) auditory-leading PSS values reported mainly for the TOJ task. We report data from two stimulus types that differed in terms of complexity--namely, (1) a flash and a click and (2) a bouncing ball and an impact sound. The same participants judged the temporal order and synchrony of both stimulus types, using three experimental methods: (1) a TOJ task with two response categories ("audio first" or "video first"), (2) an SJ task with two response categories ("synchronous" or "asynchronous"; SJ2), and (3) an SJ task with three response categories ("audio first," "synchronous," or "video first"; SJ3). Both stimulus types produced correlated PSS estimates with the SJ tasks, but the estimates from the TOJ procedure were uncorrelated with those obtained from the SJ tasks. These results suggest that the SJ task should be preferred over the TOJ task when the primary interest is i n perceived audio-visualsynchrony.     

Visual representation of eye gaze is coded by a nonopponent multichannel system

To date, there is no functional account of the visual perception of gaze in humans. Previous work has demonstrated that left gaze and right gaze are represented by separate mechanisms. However, these data are consistent with either a multichannel system comprising separate channels for distinct gaze directions (e.g., left, direct, and right) or an opponent-coding system in which all gaze directions are coded by just 2 pools of cells, one coding left gaze and the other right, with direct gaze represented as a neutral point reflecting equal activation of both left and right pools. In 2 experiments, the authors used adaptation procedures to investigate which of these models provides the optimal account. Both experiments supported multichannel coding. Previous research has shown that facial identity is coded by an opponent-coding system; hence, these results also demonstrate that gaze is coded by a different representational system to facial identity.     

Community and health facility influences on contraceptive method choice in the Eastern Cape, South Africa

CONTEXT: Although a growing number of studies have examined how community factors influence contraceptive use, few have explored how such factors affect method choice. METHODS: Data from the 1998 South Africa Demographic and Health Survey and the 1998 Eastern Cape Facility Survey were used to examine community and health facility influences on the method choices of 1,165 women aged 15-49 who lived in the Eastern Cape. Relative risk ratios from multilevel multinomial models assessed how method choice varied between communities. RESULTS: The likelihood of using the pill or a more permanent method rather than the injection rose with the proportion of women in a community who controlled their earnings (risk ratios, 3.2 and 3.8, respectively). In communities with higher proportions of females with only a primary education, women were less likely to use the pill instead of the injection (0.1). Higher doctor staffing levels were associated with a greater likelihood of using the pill or a more permanent method (1.5 and 1.4), and having more expired methods in stock was associated with increased use of a more permanent method (2.1). Several facility factors were associated with a decreased likelihood of using the pill rather than the injection: higher numbers of community health workers in an area and higher numbers of facility nurses who had received training on HIV/AIDS in the last year (0.9 for each). Yet a substantial amount of variation in method choice was not accounted for by these variables. CONCLUSION: Future research should emphasize the collection of community-level data on structural, behavioral and cultural factors to help explain the variation in method choice between communities.     

Spatial tapping interferes with the processing of linguistic spatial relations.

Simple spatial relations may be represented either in a propositional format that is dependent on verbal rehearsal or in a picture-like format that is maintained by visual-spatial rehearsal. In sentence-picture and picture-picture verification tasks, we examined the effect of an articulatory suppression and a spatial tapping dual task on the encoding of simple spatial relations (e.g., triangle left of circle). Articulatory suppression did not interfere, while spatial tapping lowered performance in both tasks. Apparently, both linguistic and perceptual inputs of simple spatial relations engaged the visual-spatial working memory. In the sentence-picture verification experiments, spatial tapping only hampered performance of participants who were classified on the basis of their RT patterns as having used a visual-spatial strategy, while it had no effect for those who were classified as having applied a verbal strategy. Therefore, this study provides converging evidence, using a dual-task methodology, that both separate verbal and visual-spatial strategies exist for the processing of simple spatial sentences.     

Face detection dissociates from face identification

We describe three experiments in which viewers complete face detection tasks as well as standard measures of unfamiliar face identification. In the first two studies, participants viewed pareidolic images of objects (Experiment 1) or cloud scenes (Experiment 2), and their propensity to see faces in these scenes was measured. In neither case is performance significantly associated with identification, as measured by the Cambridge Face Memory or Glasgow Face Matching Tests. In Experiment 3 we showed participants real faces in cluttered scenes. Viewers’ ability to detect these faces is unrelated to their identification performance. We conclude that face detection dissociates from face identification.     

Communication Via Instant Messenger: Short- and Long-Term Effects

Ersatz social engagement theory (Green & Brock, 1998, 2003) suggests that individuals may be drawn to mediated interactions because of their ease, lack of risk, and immediate gratification, but that these interactions may be less rewarding over the long term. In Study 1 ( N = 42), participants' moods were measured before and after engaging in a conversation with a stranger either online (instant messenger) or face to face. Participants became slightly less tense and less angry regardless of which condition they were in, but significantly happier when they were in the instant messenger (1M) condition. The increased happiness after an IM rather than face-to-face conversation was especially pronounced among women. Study 2 ( N = 101) was a survey of students' Internet use and other extracurricular activities. Students did not appear to be substituting Internet use for other forms of extracurricular engagement. However, IM use was associated with feeling that one used the Internet too much, and reduced life satisfaction.     

Culture, Communication, and Competence: A Commentary on Variables Affecting Social and Academic Behavior

The editors of this special issue have recruited six papers focused on the ways that language and communication interact with culture to influence student behavior. Two themes that emerge from these papers are the fundamental role of communication in learning and living, and the impact of culture on the functions of communication. The present commentary is offered in admiration for the work of the authors, and with the goal of emphasizing common messages that may guide both future research and practice.     

Decreased load on general motor preparation and visual-working memory while preparing familiar as compared to unfamiliar movement sequences

Learning movement sequences is thought to develop from an initial controlled attentive phase to a more automatic inattentive phase. Furthermore, execution of sequences becomes faster with practice, which may result from changes at a general motor processing level rather than at an effector specific motor processing level. In the current study, we examined whether these changes are already present during preparation. Fixed series of six keypresses, either familiar or unfamiliar, had to be prepared and executed/withheld after a go/nogo signal. Reaction time results confirmed that familiar sequences were executed faster than unfamiliar sequences. Results derived from the electroencephalogram showed a decreased demand on general motor preparation and visual-working memory before familiar sequences as compared to unfamiliar sequences. We propose that with familiar sequences the presetting segments of responses is less demanding than with unfamiliar sequences, as familiar sequences can be regarded as less complex than unfamiliar sequences. Finally, the decreasing demand on visual-working memory before familiar sequences suggests that sequence learning indeed develops from an attentive to an automatic phase.     

The effect of figural manipulations on brightness differences in the Benary cross

The Benary cross is a classical demonstration showing that the perceived brightness f an area is not solely determined by its luminance, but also by the context in which it is embedded. Despite the fact that two identical grey triangles are flanked by an equal amount of black and white, one of the triangles is perceived as being lighter than the other. It has been argued that the junctions surrounding a test area are crucial in determining brightness. Here, we explored how different aspects influencing perceptual organisation influence perceived figure-background relations in the Benary cross and, with that, the perceived brightness of the triangular patches in our stimuli. The results of a cancellation task confirm that the alignment of contours at junctions indeed has a strong influence on an area's brightness. At the same time, however, the Benary effect is also influenced by the overall symmetry of the cross and its orientation.