The role of infant soothability in the relation between infant negativity and maternal sensitivity

Maternal perceptions of infant soothability moderated the relation between negative infant temperament and maternal sensitivity. Infant negative temperament and maternal sensitivity were significantly positively related when maternal perception of infant soothability was high and significantly negatively related when maternal perception of infant soothability was low.     

Mathematics learning disability in girls with Turner syndrome or fragile X syndrome

Two studies were carried out to examine the persistence (Study 1) and characteristics (Study 2) of mathematics learning disability (MLD) in girls with Turner syndrome or fragile X during the primary school years (ages 5-9 years). In Study 1, the rate of MLD for each syndrome group exceeded the rate observed in a grade-matched comparison group, although the likelihood of MLD persisting through the primary school years was comparable for all three groups. In Study 2, formal and informal math skills were compared across the syndrome groups, a normative group, and children from the normative group who had MLD. Few differences were observed between the Turner syndrome and normative groups. Despite having rote counting and number representation skills comparable to those in the normative group, girls with fragile X had difficulty with counting rules (e.g., cardinality, number constancy). However, this difficulty did not distingush them from the MLD group. Overall, counting skills appear to distinguish the Turner syndrome and fragile X groups, suggesting that the specificity of math deficits emerges earlier for fragile X than Turner syndrome.     

Phenomenology and delusions: Who put the ‘alien’ in alien control?

Although current models of delusion converge in proposing that delusions are based on unusual experiences, they differ in the role that they accord experience in the formation of delusions. On some accounts, the experience comprises the very content of the delusion, whereas on other accounts the delusion is adopted in an attempt to explain an unusual experience. We call these the endorsement and explanationist models, respectively. We examine the debate between endorsement and explanationist models with respect to the 'alien control' delusion. People with delusions of alien control believe that their actions and/or thoughts are being controlled by an external agent. Some accounts of alien control (e.g., ) are best thought of in explanationist terms; other accounts (e.g., ) seem more suited to an endorsement approach. We argue that recent cognitive and neurophysiological evidence favours an endorsement model of the delusion of alien control.     

Delay of gratification: impulsive choices and problem behaviors in early and late adolescence

High school students were offered a monetary incentive for participating in research. They were given a choice between a smaller fee immediately or a larger fee one week later. Compared to students who delayed gratification, those who chose the immediate fee showed more self-regulatory deficits. They showed greater involvement with cigarettes, alcohol, and marijuana, had a poorer self-concept and underperformed academically. A replication study with middle-school students and different reward parameters yielded equivalent results. Younger adolescents who chose the immediate monetary incentive showed a similar pattern of problem behaviors as the high school students. The findings indicate that this simple choice-delay procedure yields an unobtrusive behavioral measure of self-regulation and offers a developmentally appropriate extension of the delay-of-gratification paradigm for use with older children and adolescents.     

Preference and resistance to change with constant- and variable-duration terminal links: independence of reinforcement rate and magnitude

Pigeons responded in a three-component multiple concurrent-chains procedure in which the variable-interval reinforcement schedules were the same across components but magnitudes differed across components. The terminal links were arranged either as a variable delay followed by presentation of a reinforcer ("variable duration") or as a fixed period of access to the schedule during which a variable number of reinforcers could be earned ("constant duration"). Relative reinforcement rate was varied parametrically across both types of conditions. After baseline training in each condition, resistance to change of terminal-link responding was assessed by delivering food during the initial links according to a variable-time schedule. Both preference and resistance to change were more sensitive to reinforcement-rate differences in the constant-duration conditions. Sensitivities of preference and resistance to change to relative reinforcement rate did not change depending on relative reinforcement magnitude. Taken together, these results confirm and extend those of prior studies, and suggest that reinforcement rate and magnitude combine additively to determine preference and resistance to change. A single structural relation linking preference and resistance to change describes all the data from this and several related studies.     

Overestimation of heights in virtual reality is influenced more by perceived distal size than by the 2-D versus 3-D dimensionality of the display

One important aspect of the pictorial representation of a scene is the depiction of object proportions. Yang, Dixon, and Proffitt (1999 Perception 28 445-467) recently reported that the magnitude of the vertical-horizontal illusion was greater for vertical extents presented in three-dimensional (3-D) environments compared to two-dimensional (2-D) displays. However, because all of the 3-D environments were large and all of the 2-D displays were small, the question remains whether the observed magnitude differences were due solely to the dimensionality of the displays (2-D versus 3-D) or to the perceived distal size of the extents (small versus large). We investigated this question by comparing observers' judgments of vertical relative to horizontal extents on a large but 2-D display compared to the large 3-D and the small 2-D displays used by Yang et al (1999). The results confirmed that the magnitude differences for vertical overestimation between display media are influenced more by the perceived distal object size rather than by the dimensionality of the display.     

Path integration from optic flow and body senses in a homing task

We examined the roles of information from optic flow and body senses (eg vestibular and proprioceptive information) for path integration, using a triangle completion task in a virtual environment. In two experiments, the contribution of optic flow was isolated by using a joystick control. Five circular arenas were used for testing: (B) both floor and wall texture; (F) floor texture only, reducing information for rotation; (W) wall texture only, reducing information for translation; (N) a no texture control condition, and (P) an array of posts. The results indicate that humans can use optic flow for path integration and are differentially influenced by rotational and translational flow. In a third experiment, participants actively walked in arenas B, F, and N, so body senses were also available. Performance shifted from a pattern of underturning to overturning and exhibited decreased variability, similar responses with and without optic flow, and no attrition. The results indicate that path integration can be performed by integrating optic flow, but when information from body senses is available it appears to dominate.     

Intervening to improve communication between parents, teachers, and primary care providers of children with ADHD or at high risk for ADHD

This study examines interventions designed to improve communication between individuals who take care of children with ADHD. A teacher rating of 6,171 elementary school children identifies 1,573 children with ADHD or with high risk for ADHD. Parent interviews and information from teachers are collected on 243 children who are randomized into treatment and control conditions and followed for 39 months. The interventions consisted of group workshops and single one-on-one tutorials with parents, teachers, and providers about the evaluation and treatment of ADHD that stressed the need for communication between the three parties. There are few significant effects on communication that are short lived. Results suggest that the interventions are insufficient to cause significant increase in communication. Future attempts to improve parent-teacher-provider coordination should be continuing rather than single-session interventions.     

The influence of exploration mode, orientation, and configuration on the haptic Müller-Lyer illusion

We studied the impact of manner of exploration, orientation, spatial position, and configuration on the haptic Müller-Lyer illusion. Blindfolded sighted subjects felt raised-line Müller-Lyer and control stimuli. The stimuli were felt by tracing with the index finger, free exploration, grasping with the index finger and thumb, or by measuring with the use of any two or more fingers. For haptic judgments of extent a sliding tangible ruler was used. The illusion was present in all exploration conditions, with overestimation of the wings-out compared to wings-in stimuli. Tracing with the index finger reduced the magnitude of the illusion. However, tracing and grasping induced an overall underestimation of size. The illusion was greatly attenuated when stimuli were felt with the index fingers of both hands. Illusory misperception was not altered by the position in space of the Müller-Lyer stimuli. No effects of changes in the thickness of the line shaft were found, but there were effects of the length of the wing endings for the smaller, 5.1 cm stimuli. The theoretical and practical implications of the results are discussed.