Some decks are better than others: the effect of reinforcer type and task instructions on learning in the Iowa Gambling Task

The Iowa Gambling Task (Bechara, Damasio, Damasio, & Anderson, 1994) has become widely used as a laboratory test of "real-life" decision-making. However, aspects of its administration that have been varied by researchers may differentially affect performance and the conclusions researchers can draw. Some researchers have used facsimile money reinforcers while others have used real money reinforcers. More importantly, the instructions participants receive have also been varied. While no differences have been reported in performance dependent on reinforcer type, no previous comparison of participants' instructions has been conducted. This is despite one set of instructions giving participants a clear hint about the nature of the task. Additionally, in previous research one set of instructions have not been used exclusively with one reinforcer type making any differential or cumulative effects of these factors difficult to interpret. The present study compared the effects of instruction and reinforcer type on IGT performance. When participants received instructions without a hint performance was affected by reinforcer type. This was not the case when the instructions included a hint. In a second IGT session performance was improved in participants who had received the hint instructions compared with those who had not.     

Consequences of lexical stress on learning an artificial lexicon

Four experiments examined effects of lexical stress on lexical access for recently learned words. Participants learned artificial lexicons (48 words) containing phonologically similar items and were tested on their knowledge in a 4-alternative forced-choice (4AFC) referent-selection task. Lexical stress differences did not reduce confusions between cohort items: KAdazu and kaDAzeI were confused with one another in a 4AFC task and in gaze fixations as often as BOsapeI and BOsapaI. However, lexical stress did affect the relative likelihood of stress-initial confusions when words were embedded in running nonsense speech. Words with medial stress, regardless of initial vowel quality, were more prone to confusions than words with initial stress. The authors concluded that non-initial stress, particularly when wor segmentation is difficult, may serve as "noise" that alters lexical learning and lexical access.     

Concreteness and item-to-list context associations in the free recall of items differing in context variability

Context variability can be defined as the number of preexperimental contexts in which a given concept appears. Following M. Steyvers and K. J. Malmberg's (2003) work, the authors have shown that concepts that are experienced in fewer preexperimental contexts generally are better remembered in episodic memory tasks than concepts that are experienced in a greater number of preexperimental contexts. The purpose of this article is to demonstrate that low context variability confers its memorial advantage because of stronger item-to-list context associations as compared with high context variability. Three experiments that use environmental context changes from study to test demonstrate that the low context variability advantage is eliminated when item-to-list context associations are not available because of environmental changes at test. In addition, the low context variability advantage is eliminated when inward processing at study prevents the formation of item-to-list context associations.     

Shared representations in body perception

The ability to understand events that happen to other people is a characteristic feature of the human mind. Here, we investigate whether the links between mental representation of one's own body and the bodies of other people could form the basis of human social representations. We studied interpersonal body representation (IBR) in a series of behavioural cueing experiments. Subjects responded to tactile events on their own body after a visual event was presented in either the corresponding anatomical location on a model's body, or in a non-corresponding location. We found that reactions were faster when the visual cue was in register with the tactile stimulation. This effect was absent when identical visual events were presented on a non-body control stimulus, suggesting a body specific mechanism for interpersonal registration of purely sensory events. Similar interpersonal systems have been demonstrated previously for the coding of action and emotion, but we believe that our results provide the first behavioural evidence for interpersonal body representation at the purely sensory level. We show that a sensory processing mechanism specific for bodies is automatically activated when viewing another person. Interpersonal body representation may be an important precursor to empathy and theory of mind. In our social world, we understand the percepts of others by registering them against the representations used to perceive our own body, and this mechanism involves an interpersonal somatotopic map.     

Beyond the hedonic treadmill: revising the adaptation theory of well-being

According to the hedonic treadmill model, good and bad events temporarily affect happiness, but people quickly adapt back to hedonic neutrality. The theory, which has gained widespread acceptance in recent years, implies that individual and societal efforts to increase happiness are doomed to failure. The recent empirical work outlined here indicates that 5 important revisions to the treadmill model are needed. First, individuals' set points are not hedonically neutral. Second, people have different set points, which are partly dependent on their temperaments. Third, a single person may have multiple happiness set points: Different components of well-being such as pleasant emotions, unpleasant emotions, and life satisfaction can move in different directions. Fourth, and perhaps most important, well-being set points can change under some conditions. Finally, individuals differ in their adaptation to events, with some individuals changing their set point and others not changing in reaction to some external event. These revisions offer hope for psychologists and policy-makers who aim to decrease human misery and increase happiness.     

The effects of unilateral grab rail assistance on the sit-to-stand performance of older aged adults

This study investigated the effects of unilateral grab rail assistance during the sit-to-stand transfer to develop an understanding of lower limb joint mechanics and whole body movement patterns. External reaction forces at the grab rail and floor interfaces were also investigated to understand the nature of the assistance provided by the introduction of unilateral upper body assistance. While 12 older aged adults performed the sit-to-stand, three-dimensional body segment kinematics were recorded to determine lower body joint motion and whole body centre of mass motion. Grab rail reaction forces and bilateral ground reaction forces were recorded to determine external reaction forces and lower body joint kinetics. Grab rail assisted conditions were compared with unassisted transfers. During grab rail assistance, a systematic asymmetry was introduced to lower limb joint kinetics, without noticeable alterations to peak lower body joint motion and whole body movement patterns. Ipsilateral net joint moments and powers decreased in the ankle and hip and increased in the knee, while the contralateral net joint moments and powers increased in the hip and decreased in the knee. Joint kinetic and kinematic responses suggest a motor control strategy that maintains symmetric sit-to-stand movement patterns by adjusting bilateral muscle control when a unilateral external reaction force is provided. Understanding the mechanical assistance that is generated during the sit-to-stand will facilitate optimal design of grab rails for older aged adults and may contribute to design for specific pathologies. Such design implementation will influence the ability of older aged adults to remain independent in the community.     

Parents' and teachers' concordance with children's self-ratings of suicidality: findings from a high-risk sample

This study examined concordance between adult and child reports of child suicidality using a sample of 1,046 8-year-old children at risk for, or having experienced, maltreatment. Concordance was low with both caregivers and teachers. For children reporting no suicidality, caregiver-child agreement was associated with few transitions in caregiver and low social withdrawal and aggression, and teacher-child agreement was associated with non-White ethnicity, good academic performance, and low thought problems. For children reporting suicidality, care-giver-child agreement was associated with perceptions of child mental health needs, aggression, and somatic complaints, and teacher-child agreement was associated with thought problems.