Carryover effects associated with the single-trial passive avoidance learning task in the young chick

The single-trial passive avoidance task is a useful procedure for examining learning and memory in the young chick. However, it has recently been suggested that discrepant results reported by different laboratories are due to differences in training procedure. The present study investigated a number of parameters surrounding the passive avoidance task, using day-old White Leghorn, Black Australorp cockerels. The results suggested that presentation of a water-dipped bead immediately after the aversive bead significantly altered retention levels. In addition, when the water-dipped bead was presented after the aversive bead, chicks failed to discriminate between beads for a period of 10 min following exposure to the aversant experience. A novel variant of the passive avoidance procedure, involving pretraining with a water-dipped red bead, training with an aversant-coated red bead, and testing with a dry red bead, was evaluated. A measure of avoidance was calculated using all three trials. It is suggested that the use of a single bead, measured both before and after the training experience and using both aversant- and water-trained controls, results in the most concise characterization of memory-related phenomena in the chick which is not contaminated by a carryover effect from the aversive training experience to the nonaversive bead.     

The formation of a generalized categorization repertoire: effect of training with multiple domains,samples, and comparisons

The present experiment explored the effects of three variables on the spontaneous categorization of stimuli in perceptually distinct and novel domains. Each of six stimulus domains was created by morphing two images that were the domain endpoints. The endpoints of the domains were male and female faces, two abstract drawings, a car and a truck, two banded-elevation satellite land images, a tree and a cat, and two false-color satellite images. The stimulus variants at each end of a domain defined two potential perceptual classes. Training was conducted in a matching-to-sample format and used stimuli from one or two domains, one or three variants per class as samples, and one or three variants per class as comparisons. The spontaneous categorization of stimuli in the untrained stimulus domains showed the emergence of a generalized categorization repertoire. The proportion of spontaneously categorized stimuli in the new domains was positively related to the number of domains and samples used in training, and was inversely related to the number of comparisons used in training. Differential reaction times demonstrated the discriminability of the stimuli in the emergent classes. This study is among the first to provide an empirical basis for a behavior-analytic model of the development of generalized categorization repertoires in natural settings.     

Congenital hypothyroidism: an analysis of persisting deficits and associated factors.

Congenital hypothyroidism (CH) is a neonatal disorder that is caused by a prolonged loss of thyroid hormone, which is essential for early brain development. While CH was once the leading cause of mental retardation, newborn screening for CH now allows for early identification and treatment. As a result, affected children now show normal physical and psychological development. Nevertheless, because they still undergo a brief but circumscribed period of thyroid hormone insufficiency, they are at risk for subtle selective impairments. This paper examines several of the persisting deficits observed in children with CH that was identified early in life by newborn screening as well as the relevant disease- and treatment-related factors contributing to such deficits. Highlighted will be (a) a weakness in visuospatial processing, which is associated with prenatal thyroid hormone insufficiency, (b) selective memory deficits associated with postnatal thyroid hormone insufficiencies, (c) a weakness in sensorimotor abilities also reflecting postnatal thyroid hormone insufficiencies, and (d) attention deficits, which are due to abnormal thyroid hormone levels at time of testing. Because these four disabilities implicate different neural substrates, the findings described presently will provide insights as to the specific time windows when different brain structures in the human critically need thyroid hormone.     

Psychometric Models of Small Group Collaborations

The social combination theory of group problem solving is used to extend existing psychometric models to collaborative settings. A model for pairwise group work is proposed, the implications of the model for assessment design are considered, and its estimation is addressed. The results are illustrated with an empirical example in which dyads work together on a twelfth-grade level mathematics assessment. In conclusion, attention is given to avenues of research that seem most fruitful for advancing current initiatives concerning the assessment of collaboration, teamwork, and related constructs.     

Motion influences gaze direction discrimination and disambiguates contradictory luminance cues

In two experiments, we investigated the role of apparent motion in discriminating left/right gaze deviation judgments. We demonstrated that discrimination accuracy and response confidence was significantly higher when the eyes were moved to the left or right, compared to when the eyes were presented in their final shifted position (static images). To dissociate the role of motion signals from luminance signals, gaze stimuli were also presented in reverse contrast. Replicating past studies polarity reversal had a profound and detrimental effect on gaze discrimination in static images, although, intriguingly, while response confidence remained low, participant performance improved as gaze angle increased. In striking contrast to these data, polarity reversal had no negative effect on performance when the eyes were moved. We discuss these findings in the context of a multiple-cue account of gaze perception.     

How work spills over into the relationship: Self‐control matters

This research investigated how and for whom experiences of the workday spill over into relationship functioning at home. Two correlational studies and one experimental study were conducted among Dutch dual‐earners with children. Moderated mediation analyses showed that work demands spill over into relationship behavior through the depletion of temporary self‐regulatory resources and subsequently a decrease in psychological availability for the partner. Whether work demands spill over into relationship behavior was dependent on dispositional self‐control in that evidence for negative spillover was only found for individuals low in dispositional self‐control. The experimental study showed that the induction of gratitude for the partner after the workday helped individuals low in dispositional control to prevent negative spillover into the partner relationship.     

Knowing When Help Is Needed: A Developing Sense of Causal Complexity

Research on the division of cognitive labor has found that adults and children as young as age 5 are able to find appropriate experts for different causal systems. However, little work has explored how children and adults decide when to seek out expert knowledge in the first place. We propose that children and adults rely (in part) on “mechanism metadata,” information about mechanism information. We argue that mechanism metadata is relatively consistent across individuals exposed to similar amounts of mechanism information, and it is applicable to a wide range of causal systems. In three experiments, we show that adults and children as young as 5 years of age have a consistent sense of the causal complexity of different causal systems, and that this sense of complexity is related to decisions about when to seek expert knowledge, but over development there is a shift in focus from procedural information to internal mechanism information.     

Mother still knows best: Maternal influence uniquely modulates adolescent reward sensitivity during risk taking

Adolescent decision‐making is highly sensitive to input from the social environment. In particular, adult and maternal presence influence adolescents to make safer decisions when encountered with risky scenarios. However, it is currently unknown whether maternal presence confers a greater advantage than mere adult presence in buffering adolescent risk taking. In the current study, 23 adolescents completed a risk‐taking task during an fMRI scan in the presence of their mother and an unknown adult. Results reveal that maternal presence elicits greater activation in reward‐related neural circuits when making safe decisions but decreased activation following risky choices. Moreover, adolescents evidenced a more immature neural phenotype when making risky choices in the presence of an adult compared to mother, as evidenced by positive functional coupling between the ventral striatum and medial prefrontal cortex. Our results underscore the importance of maternal stimuli in bolstering adolescent decision‐making in risky scenarios.