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.     

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.     

Sex differences in landmark learning by children aged 5 to 12 years

Previous research has shown that men and boys learn routes faster and with fewer errors than do women and girls. Research with adults suggests that men use Euclidean cues when learning a route, whereas women use landmark-based strategies. The strategies used by children have received little study. In Exp. 1, 50 boys and girls, ages 5 to 12 years, were shown a map that contained only landmarks (no streets or roads) and were asked to learn a route consisting of 23 of the landmarks. The children used a pointer to trace the route on the map to a criterion of two successive trials without errors. The performance of boys and girls did not differ significantly on this route-learning task on three measures (number of trials to reach criterion, total time to reach criterion, and total number of errors). In Exp. 2, 52 boys and girls, ages 5 to 12 years, were shown the same map as in Exp. 1 and were asked to learn a route consisting of 12 landmarks. The children traced the route by picking pictures of landmarks in the correct order from a stack of cards with pictures of landmarks on them. Girls made significantly fewer errors than boys on this route-learning task in Exp. 2, and a significantly larger number of girls than boys completed the task. None of the boys in the 5- to 6-yr.-old age group learned the route. When Euclidean cues were minimized in Exp. 2, boys made more errors and took as much time as girls to reach the criterion of two successive correct trials.     

Depressive deficits in forgetting

The aim of this study was to investigate whether difficulties in forgetting (like difficulties in remembering) are associated with depressive states. First, dysphoric and nondysphoric students learned 40 word pairs, each consisting of a positive or negative adjective and a neutral noun (target). Next, the students practiced responding with some targets and suppressing others, when given the adjective as cue, for a varied number of repetitions. On the final test, they were told to disregard the prior instruction to suppress and to recall the target associated with every cue. Compared with nondysphoric students, dysphoric students recalled similar percentages of targets from sets assigned for response practice but higher percentages from sets assigned for suppression practice. The degree of forgetting showed some mood-congruent tendencies and was significantly correlated with self-report measures of rumination and unwanted thoughts.     

Preservation of implicit memory in adult children of alcoholics

The authors investigated implicit memory in 21 adult children of alcoholics (ACAs) and 24 control individuals (all college undergraduates) who performed a serial reaction time task (SRT) to evaluate their implicit memory performance and their formation of new associations. Each group was presented with 5 blocks of 100 trials per block in which Blocks 1-4 contained a 10-item repeating sequence; Block 5 was a pseudo-random sequence. The latency difference between Block 4 and Block 5 presumably measure implicit memory. The amount of implicit memory did not differ (in ms) between the ACAs (M = 55 ms) and the controls (M = 67 ms). Implicit memory (at least as measured by the SRT task) appears to be preserved in ACAs.