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.     

Stimulus repetition effects and the dimension-feature distinction in alternative targets

The negative repetition effect (NRE) refers to a poorer perception of the target in noise-same-as-target than in noise-alternative-target displays. Using the parenthesis as target and noise that are either identical or different in orientation, we tested predictions derived from a feature-specific inhibition model (Bjork & Murray, 1977) that explains the NRE as arising from inhibitory interactions among channels handling identical inputs. Contrary to our expectation of evidence for orientation-specific inhibition, a positive repetition effect (PRE) was observed. We also found a PRE for the dimension target sets whose stimuli differ only in orientation and an NRE for the feature target sets whose stimuli differ in the number of elements. Further experiments that systematically varied relationships between alternative targets indicate that these basic findings, termed the stimulus attributes effects, do not arise from pattern masking, perceptual strategies, or response bias.     

Inquiry into intentional systems I: Issues in ecological physics

Summary The role of intention in guiding the behavior of goal-directed systems is a problem that continues to challenge behavioral science. While it is generally agreed that intentional systems must be consistent with the laws of physics, there are many obvious differences between inanimate, physical systems and sentient, intentional systems. This suggests that there must be constraints over and above those of physics that govern goal-directed behavior. In this paper it is suggested that generic properties of self-organizing mechanisms may play a central role in the origin and evolution of intentional constraints. The properties of self-organizing systems are first introduced in the context of simple physical systems and then extended to a complex (biological) system. Whereas behavior of an inanimate physical system is lawfully determined by force fields, behavior of an animate biological system is lawfully specified by information fields. Biological systems are distinguished from simple physical systems in terms of their ubiquitous use of information fields as special (biological and psychological, social, etc.) boundary conditions on classical laws. Unlike classical constraints (boundary conditions), informational constraints can vary with time and state of the system. Because of the nonstationarity of the boundary conditions, the dynamic of the system can follow a complex trajectory that is organized by a set of spatially and temporally distributed equilibrium points or regions. It is suggested that this equilibrium set and the laws that govern its transformation define a minimal requirement for an intentional system. One of the benefits of such an approach is that it suggests a realist account for the origin of semantic predicates, thereby providing a basis for the development of a theory of symbolic dynamics. Therefore, the principles of self-organization provide a comprehensive basis for investigating intentional systems by suggesting how it is that intentions arise, and by providing a lawful basis for intentional behavior that reveals how organisms become and remain lawfully informed in the pursuit of their goals.     

Chicks Injected with Antisera to either S-100α or S-100β Protein Develop Amnesia for a Passive Avoidance Task

The cellular expression of S-100β protein is upregulated in Alzheimer's disease and in Down's syndrome, and this protein has been implicated in memory-related processes in laboratory animals. However, the possibility that the α subunit of S-100 is also involved in memory has not yet been examined. In the present study, day-old black Australorp white Leghorn cockerel chicks (Gallus domesticus) received injections of monoclonal antisera to S-100α (1:50) or S-100β (1:500) into each hemisphere immediately after training on a one-trial passive avoidance task. The chicks displayed significantly lower retention levels than control birds that had been injected with antisera to carbonic anhydrase, or with saline (p< .01). S-100α antisera had an amnestic effect when injected between 0 and 20 min after training, with memory deficits occurring from 30 min postlearning, at the point of transition between the A and the B phases of the Gibbs-Ng intermediate memory stage. By contrast, the S-100β antisera needed to be injected either 5 min before or immediately after training and produced amnesia 10 min earlier, at the start of the A phase of the intermediate memory stage. We conclude that the two subunits of the S-100 protein are required at different points in the sequence of events leading to the consolidation of passive avoidance memory.     

Internalizing and externalizing characteristics of sexually and/or physically abused children

This study evaluates the behavioral consequences of childhood abuse (sexual, physical, or both), with particular focus on prevalence of posttraumatic stress disorder (PTSD). Three abuse type groups and nonabused controls were contrasted on behavioral rating scales and on structured psychiatric interview data. The participants (109 abused children and 16 normal control children) were recruited from Arkansas Children’s Hospital and local agencies for abused children. As expected, proportionately more females than males were sexually abused. Overall, males were rated as more disturbed than females. Type of abuse did not consistently influence behavioral ratings. Externalizing scores were significantly higher than internalizing scores in all abused groups. PTSD was diagnosed in 50% of the abused children, with a higher rate for boys who had been sexually abused as opposed to physically abused only (58% versus 13%). The most frequent comorbid condition with PTSD was Separation Anxiety. Sexually abused boys were hospitalized for psychiatric treatment at a higher rate than were other abused children.     

Encoding, repetition, and the mirror effect in recognition memory: Symmetry in motion

Attention/likelihood theory has been used to explain the mirror effect in recognition memory. The theory also predicts that any manipulation that affects the recognition of old items will also affect recognition of the new items—more specifically, that all the underlying distributions will move and that they will move symmetrically on the decision axis. In five experiments, we tested this prediction. The first two experiments used encoding tasks during study to change recognition performance for high- and low-frequency words. The results show symmetrical dispersion of the underlying distributions. The final three experiments used repetition to increase recognition performance. Repetition produced a symmetrical pattern of movement that was different from that produced by encoding task. This pattern is, however, also covered by attention/likelihood theory. A further extension of the theory was used to predict response times.     

Compensation for Jaw Fixation by Aphasic Patients

The ability to compensate for fixation of the jaw by a bite block was investigated in 6 nonfluent aphasics, 6 fluent aphasics, and 10 normal control subjects. Acoustic analyses of the vowels [i u a æ] and fricatives [s s] revealed substantial but incomplete compensation for the perturbation in all three subject groups. Perceptual identification scores and quality ratings by naive and phonetically trained listeners indicated poorer identification of the high vowels [i u] under compensatory conditions relative to normal production. Of particular interest was the fact that all three groups of subjects exhibited similar patterns of results. The findings suggest that any deficit in speech motor programming demonstrated by the nonfluent aphasic patients did not affect compensatory abilities. Results are discussed with respect to normal speech adaptation skills and the nature of articulatory breakdown in nonfluent aphasia.     

The Effects of Food and Gender on Interpersonal Perceptions

Male and female subjects provided ratings of personal traits, femininity and masculinity, and total caloric consumption for a female or a male target based on the type of diet she or he had allegedly consumed. The gender associated with the foods presented for each dietary profile was manipulated. Results showed that Target Gender and Dietary Profile significantly affected impression ratings and calorie estimates. Both male and female subjects perceived male eaters and those who ate a feminine diet more favorably. Results are discussed in terms of the different underlying expectations held for males and females when food consumption is involved during the impression formation process.     

A preliminary scale to measure connected and separate knowing: The Knowing Styles Inventory

The present investigation reported the development and validation of the Knowing Styles Inventory (KSI), a scale to measure connected and separate knowing [M. F. Belenky, B. M. Clinchy, N. R. Goldberger, and J. M. Tarule (1986), Women's Ways of Knowing: The Development of Self, Voice, and Mind New York, Basic Books]. In Study 1, principal components analyses for samples of females (N = 300) and males (N = 253) yielded two components, Connected and Separate Knowing. Studies 2 and 3 focused on females exclusively. The results indicated adequate test—retest reliability and internal consistency for both components. Additionally, Connected Knowing was positively correlated with empathic concern, perspective-taking, social desirability, and the femininity factor of the Bem Sex Role Inventory (BSRI). Separate Knowing was positively correlated with the masculinity factor of the BSRI and negatively correlated with social desirability. Suggestions for future research were presented.The authors wish to thank Jill Mattuck Tarule for the insight that she offered in the early stages of this project, and they wish to acknowledge the contribution of Nicole Bressler who participated in item development.