Preload and isometric force variability

Two experiments are reported, which examined the relative contributions of preload (resting force level), change of force, and the time taken to achieve the force in determining isometric force variability. The findings showed that change of force is the strongest determiner of peak force variability but that preload and time to peak force have smaller though systematic effects. A formula that predicts peak force variability is proposed, with preload as an additive effect to the ratio between the change of force level and the square root of time to peak force. These findings confirm that these three impulse variables are significant in predicting force variability and that the impact of rate of force on peak force variability is nonlinear.     

Temporal learning in 4 1/2- and 6-year-old children: role of instructions and prior knowledge

The present study investigates effects of different types of instructions (high-rate, interval, and minimal) during training with a fixed-interval schedule as a function of prior acquired temporal knowledge. A pretest was used to assess 4 1/2- and 6-year-old children's ability to understand the temporal parameters of a fixed-interval schedule of reinforcement. The results as a whole show that the control exerted by instructions given by the experimenter or elaborated by the subjects themselves on fixed-interval performance of young children depends on the interaction of two factors: development of verbal self-control skills and mastery of knowledge required by the rules forming the instructions.     

Relationships between study organization, retrieval organization, and general and strategy-specific memory knowledge in young children

The present study examined relationships between young children's memory knowledge and their use of taxonomic and color memory organization. Forty-eight 5-, 6-, and 7-year-olds were administered metamemory tests of organization-strategy knowledge and general memory knowledge, and were tested on two study-recall tasks before, and two study-recall tasks after, training in the use of color or taxonomic organization. Study organization (grouping) scores were low before training, but improved significantly in post-training tasks. Training effects were less pronounced for retrieval organization (clustering) and did not occur for item recall. Relationships between taxonomic study and retrieval organization were apparent only for the 7-year-olds, while relationships between color organization at study and retrieval were not apparent at any age level. Relationships between metamemory, strategy-use, and recall proficiency were evident on some tasks for 7-year-olds, but not for younger children. Although teacher ratings of the children's mastery orientations were also found to be related to recall proficiency for the older subjects, specific strategy knowledge was a more consistent correlate of strategy use and amount recalled.     

A test of perceptual enhancement with peripherally presented letter pairs

The present study was conducted to determine whether sensitivity to a member of a pair of stimulus letters projecting to the parafovae would be improved by presenting that member at fixation. The effect was examined for the pair member appearing at a constant distance from fixation, which always was flanked to its inner or outer side. Contrary to expectations based upon results reported by Geiger and Lettvin (1986), observed accuracy changes were found to be due to response bias rather than to sensitivity enhancement.     

Maternal depressed mood and perceptions of child temperament

Research has suggested that women who experience postpartum depression are subsequently more likely to perceive their preschool-aged children as temperamentally difficult and maladjusted. However, previous studies have not controlled for the effects of concurrent depression levels on maternal ratings of child temperament or evaluated the accuracy of maternal reports. In the present study we assessed maternal and paternal ratings of child temperament 2 years after subjects had participated in a study of postpartum depression. The findings indicate that correlations between postpartum depression and subsequent child temperament ratings were accounted for statistically by concurrent levels of depression. Although fathers' ratings corroborated some aspects of maternal perceptions, levels of parental agreement were only moderately high. Moreover, discrepancies between the parents' reports were significantly associated with maternal depression, indicating that parental disagreement is more likely when the wife is dysphoric.     

When cognitive exertion does not yield cognitive gain: toward an informational explanation of learned helplessness

This study tested a new information-processing explanation of learned helplessness that proposes that an uncontrollable situation produces helplessness symptoms because it is a source of inconsistent, self-contradictory task information during problem-solving attempts. The flow of such information makes hypothesis-testing activity futile. Prolonged and inefficient activity of this kind leads in turn to the emergence of a state of cognitive exhaustion, with accompanying performance deficits. In 3 experiments, Ss underwent informational helplessness training (IHT): They were sequentially exposed to inconsistent task information during discrimination problems. As predicted, IHT was associated with subjective symptoms of irreducible uncertainty and resulted in (a) performance deterioration on subsequent avoidance learning, (b) heightened negative mood, and (c) subjective symptoms of cognitive exhaustion.     

Depressive self-presentation: beyond self-handicapping

An experiment was conducted to examine the notion that depressives' responses would reflect a protective self-presentation style (Hill, Weary, & Williams, 1986), the underlying goal of which would be the avoidance of future performance demands and potential losses in self-esteem. In this study, depressed and nondepressed Ss were asked to perform a relatively simple visual-motor task. Half of the depressed and half of the nondepressed Ss were told that if they were successful at the task, they would be asked to perform a 2nd, similar task. The remaining Ss were given no such expectation of future performance. We predicted and found that depressed compared with nondepressed Ss strategically failed at the task when presented with the possibility of future performance and further losses in esteem. Moreover, this strategic failure was associated with some costs; depressed-future performance expectancy Ss experienced more discomfort or negative affect as a result of their performance. The relationship between this depressive self-presentation and self-handicapping strategies is discussed.     

Victims' perceptions of social support: what is helpful from whom?

Although research has demonstrated that social interactions influence psychological well-being, little is known about what specific actions victims of stressful life events experience as helpful or unhelpful. Wortman and Dunkel-Schetter (1979) previously suggested that victims frequently experience rejection, withdrawal, and communication problems with those close to them. To address these issues, 55 cancer patients were interviewed concerning the specific actions they found to be helpful or unhelpful from several potential support providers: spouse, other family members, friends, acquaintances, others with cancer, physicians, and nurses. The data indicated that the Wortman and Dunkel-Schetter victimization model applied better to interactions with friends and acquaintances than to interactions with close family members. In addition, support was found to be partially dependent on the source: Particular actions were perceived to be helpful from some but not other network members. Implications for theory and research on social support are discussed.     

On-line and memory-based modification of attitudes: determinants of message recall-attitude change correspondence

Experiments investigated the impact of message elaboration on attitude change-message recall correspondence when attitude change occurs in an on-line (as attitude-relevant information is received), or memory-based (on the basis of retrieved attitude-relevant information) fashion. In 2 experiments, Ss' processing goals were manipulated to increase or inhibit on-line change and message elaboration. As predicted, Ss reported postexposure attitudes more rapidly in on-line vs memory-based conditions. Decreased message elaboration increased attitude-recall correspondence, regardless of when attitude change occurred. Increased elaboration produced elaboration-attitude judgment correspondence. Results suggest that recall of message content will best predict persuasion when message content is encoded free of elaborations, regardless of when attitude change occurs.     

Expectancy models of alcohol use

The primary goal of the present article is to compare expectancy models with competing attitude models of alcohol use. First, several methodological issues in expectancy research were addressed, to more adequately compare the theoretical models. Study 1 examined the effect of possible self-report biases on associations among expectancy constructs and alcohol use. In Studies 2 and 3, the basic distinction between general factors of positive and negative alcohol expectancies was investigated in both cross-sectional and prospective models. Alternative predictions that were based on competing expectancy and attitude theories were evaluated primarily in Study 3. Results from these studies supported the validity of the expectancy constructs and the proposed distinctions among expectancy and attitude constructs-in terms of strong discriminant validity, absence of self-report bias, and differential prediction of alcohol use. Furthermore, the findings favored certain expectancy models over alternative attitude models of alcohol use, reaffirming the usefulness of the expectancy framework.