Mental representation of a line when patients with left unilateral spatial neglect bisect it: A study with an endpoint reproduction task

Patients with left unilateral spatial neglect (USN) typically place the subjective midpoint to the right of the objective centre. Based on the previous findings (e.g., Ishiai et al. 1989, Brain, 112, 1485), we hypothesized that the patients with left USN may see the representational image of a line that extends equally towards either side of the subjective midpoint depending not upon the information about the leftward extent. The present study tested whether patients with left USN would place the subjective midpoint at the centre of their mental representation of the line. The participants were 10 patients with left USN and 10 neurologically healthy controls. We devised a new ‘endpoint reproduction task’ using a computer display with a touch panel to seek the representational image when patients with left USN bisect lines and asked the participants to reproduce the location of the right or left endpoint after bisecting lines. The results showed that the representational image of the bisected line depends primarily on the location of the objective right endpoint, not on the location of the objective left endpoint in space. The analyses of the estimated right and left representational extents confirmed our hypotheses that patients with left USN would bisect a line seeing the representational line image that centred across their subjective midpoint. We believe that the findings of the present study with the use of the endpoint reproduction task will contribute to a better understanding of the visuospatial process underlying line bisection of patients with left USN.     

Flexible learning and use of multiple-landmark information by pigeons (Columba livia) in a touch screen-based goal searching task

Three touch screen-based experiments were conducted to investigate whether pigeons would learn to use configural information about a goal's location in relation to a multiple-landmark array. In Experiment 1, 4 pigeons (Columba livia) were trained to peck a computer monitor at a location that constituted the third vertex of a hypothetical triangle defined by 2 different landmarks. The landmarks appeared in 3 orientations during the training, and the pigeons' goal-searching ability easily transferred to the landmarks presented in 3 novel orientations. Each landmark was asymmetric, so we next examined whether the pigeons used (a) the small-scale, local orientation information that could be inferred from each landmark individually, or (b) the large-scale, configural information that could be inferred from the spatial arrangement of multiple landmarks taken as a whole. Even when each single landmark appeared by itself, the pigeons were able to locate the goal accurately, suggesting that the large-scale, configural information was not essential. However, when 1 landmark locally pointed to a location that was consistent with the triangular configuration and the other landmark locally pointed to a different location, the pigeons predominantly pecked at the configurally array-consistent location. These results suggest that the pigeons redundantly learned both the large-scale, configural strategy and the local, single-landmark strategy, but they mainly used the latter information, and used the former information solely to disambiguate conflicts when the 2 landmarks pointed toward different targets. Such flexible learning and use of redundant information may reflect the pigeons' adaptation to unstable wild environments during their evolutionary history.     

Visual experience influences 12-month-old infants' perception of goal-directed actions of others

In the present study, we investigated whether infants' own visual experiences affected their perception of the visual status of others engaging in goal-directed actions. In Experiment 1, infants viewed video clips of successful and failed goal-directed actions performed by a blindfolded adult, with half the infants having previously experienced being blindfolded. The results showed that 12-month-old infants who were previously blindfolded preferred to look longer at the demonstrator's successful actions, whereas no such preference was observed in 8-month-old infants. In Experiment 2, infants watched the same 2 actions when the adult demonstrator was not blindfolded. The responses of 12-month-old infants were the opposite of those observed in Experiment 1: they showed a preference for the failed actions. These findings suggest that previous experience influenced the subsequent perception of others' goal-directed actions in the 12-month-old infants. We favor the interpretation that the preference for the successful actions in the 12-months-old infants provided with blindfolded experience demonstrates the influence of perceptual experience on considering the visual status of others engaging in goal-directed actions.     

Imitation of intentional manipulatory actions in chimpanzees (Pan troglodytes)

In this study, the authors investigated the understanding of other's actions in 5 adult chimpanzees (Pan troglodytes). A human demonstrated an attempt to open different containers. Each container required a different motor pattern to open it. Along with the container, a 2nd object was made available. After a free play period in which the chimpanzees' natural behaviors toward the objects were recorded, the authors tested the following 2 phases: The demonstrator (a) tried but failed to open and (b) opened the container successfully, with 1 of 2 alternative strategies, either using an "irrelevant tool" or by hand. The chimpanzees did not reproduce the demonstrator's motor patterns precisely but did reproduce the demonstrated strategies in both phases. These results suggest that chimpanzees anticipate the intentions of others by perceiving the directionality and causality of object(s) as available cues.     

Are effects of emotion expression on trait impressions mediated by babyfaceness? Evidence from connectionist modeling

Two studies provided evidence that bolsters the Marsh, Adams, and Kleck hypothesis that the morphology of certain emotion expressions reflects an evolved adaptation to mimic babies or mature adults. Study 1 found differences in emotion expressions' resemblance to babies using objective indices of babyfaceness provided by connectionist models that are impervious to overlapping cultural stereotypes about babies and the emotions. Study 2 not only replicated parallels between impressions of certain emotions and babies versus adults but also showed that objective indices of babyfaceness partially mediated impressions of the emotion expressions. babyface effects were independent of strong effects of attractiveness, and babyfaceness did not mediate impressions of happy expressions, to which the evolutionary hypothesis would not apply.     

Functional visual field in a rapid serial visual presentation task

Dynamic temporal change in the size of functional visual field was measured using a dual task: a peripheral task in which one square in a background pattern of squares was changed in shape to a dot; and a central task involving the rapid serial visual presentation of a sequence of letters (RSVP task). The temporal lag between the occurrences of the dot and the RSVP target was manipulated. University students were asked to detect the dot and to depress a mouse button as quickly as possible while searching for the RSVP target among a sequence of distracter letters. The abrupt change in the shape of a background square in the peripheral task caused a processing deficit in the RSVP task at relative lags from –3 to –1 (255 ms to 85 ms before presentation of the RSVP target), but the encoding and retaining processes involved in identifying the RSVP target did not impair the detection of the peripheral dot. The functional visual field was found to expand while participants were performing the dual task, suggesting that preattentive detection is affected by general attentional activity.     

A re-examination of the misinformation effect by means of visual and verbal recognition tests

Abstract: Two experiments were carried out to investigate the factors that produce the misinformation effect (Loftus, 1979a). Experiment 1 of the present study using the visual recognition test was a replica of Experiment 1 of Loftus, Miller, and Burns (1978). The misinformation effect was not found. Experiment 2 differed from Experiment 1 in the following respects: the modality of recognition test was varied between visual and verbal; memorableness (ease of memorization) of the critical objects was varied. The results of Experiment 2 suggest that the original visual memory might be more likely to be recovered with a visual recognition test than with a verbal recognition test, and that the postevent information would not necessarily interfere effectively with memory of an original object of too high or low memorableness, while it works well on objects of intermediate memorableness.     

Factors influencing imitation of manipulatory actions in chimpanzees (Pan troglodytes).

The purpose of the study was to investigate what kind of factors determine the degree of difficulty for chimpanzees (Pan troglodytes) when they imitate actions. Five adult chimpanzees were instructed to perform 48 arbitrary manipulatory actions consisting of different bodily motor patterns and object directionality. Results showed that actions in which an object is directed toward another external location (another object and one's own body) were easier to perform than those that involved manipulating a single object alone. Actions involving unfamiliar motor patterns were more difficult to perform than those involving familiar motor patterns that were already present in the subject's repertoire. Error responses were characterized as perseverative repetition of previously instructed actions. These findings suggest that chimpanzees find the directionality of manipulated objects a more salient cue than details of the demonstrator's body movements performing the manipulation.     

Gender and social relationships among the never-married

This research explores the social networks among the growing numbers of men and women who have never married. We use a representative sample of 193 never-married men and 217 never-married women, of whom 73% of the men and 60% women of the were white and 16% of the men and 20% of the women were black. We hypothesize that single women have a more extensive social network than do men. Second, we investigate the impact of gender roles and norms of filial responsibility and selected sociodemographic variables upon social interaction by gender. Our findings indicate that gender differences are not as anticipated: (1) while never-married women interact more frequently with relatives than do never-married men, no differences were noted among friendship or neighborhood networks; (2) time spent in social interaction was more likely to differ by marital status than it was by gender; (3) compared to married persons, the never-married are overrepresented in the extreme categories of interaction, both isolated and very active; (4) gender role ideology and filial responsibility did not significantly predict social interaction for either men or women, with the exception that, among never-married men, those with lower expectations of filial responsibility spent more time with friends.The National Survey of Families and Households was funded by a grant (HD21009) from the Center for Population Research of the National Institute of Child Health and Human Development. The survey was designed and carried out at the Center for Demography and Ecology at the University of Wisconsin—Madison under the direction of Larry Bumpass and James Sweet. The fieldwork was done by the Institute for Survey Research at Temple University. The original collectors of the data do not bear any responsibility for the analyses or the interpretations presented here.     

AIDS and Perceived Change in Sexual Practice: An Analysis of a College Student Sample from California and Iowa1

The objective of this study was to examine the impact of belief about transmissibility of AIDS and concern about the disease on perceived changes in premarital sexual practices. It was posited that changes in sexual practices are most likely to occur when college students have more certainty about AIDS transmission and greater concern about AIDS. Based on this proposition, dating patterns, premarital sexual permissiveness, attitudes toward homosexuality, sexual orientation, and students' objective perception of AIDS as a problem were used as predictors of concern about AIDS and certainty of sexual transmission. Using a sample of 587 students in the state universities of California and Iowa and focusing on one type of sexual practices (i.e., condom use), it was found that concern about AIDS strongly increases the likelihood of using condoms. Contrary to our prediction, certainty about sexual transmission of AIDS was found to have a marginal effect on students' likelihood of condom use. Furthermore, it was found that monogamous dating, sexual permissiveness, and the degree of perception of AIDS as a problem significantly increase the likelihood of condom use if they are mediated by personal concern about AIDS. The implications are discussed with respect to the usefulness of a theoretical approach and its findings for education on AIDS prevention among college students.