Force variability in isometric responses

In the present study we examined the contribution of different impulse parameters to peak force variability in an isometric task. Five experiments are reported that each held constant a different impulse parameter while allowing the other impulse parameters to vary. The results indicate that change in force level is the parameter that has the greatest effect on peak force variability, although time to peak force and preload also systematically influence response variability. A formula that accommodates the relation between impulse parameters and force variability is proposed. The data suggest that even in isometric tasks, it is the force-time properties of the impulse, rather than discrete parameters such as peak force, that determine the outcome variability.     

Overanxious disorder: An examination of developmental differences

Differences between a clinical sample of younger (ages 5 to 11) and older (ages 12 to 19) children meeting DSM-III criteria for overanxious disorder (OAD) were examined. Younger and older children were compared in terms of (1) the rates of OAD diagnoses occurring in the two age groups, (2) sociodemographic characteristics, (3) symptom expression, (4) association with other forms of maladjustment, and (5) self-reported anxiety and depression. The prevalence of OAD diagnoses and sociodemographic characteristics did not differ. Although younger and older OAD children showed similar rates of most specific DSM-III OAD symptoms, older children presented with a higher total number of overanxious symptoms than younger children. Older children more frequently exhibited a concurrent major depression or simple phobia, whereas younger OAD children more commonly had coexisting separation anxiety or attention deficit disorders. Older OAD children reported significantly higher levels of anxiety and depression on self-report measures. Findings indicated that the expression of OAD varies by developmental level.     

Familiar idiom comprehension

Sentences containing idioms used either literally or figuratively were presented repeatedly for 100 msec per presentation. Half of the sentences were preceded by a paragraph. The number of presentations required to read the sentences and cued recall of the sentences were recorded. The serial brief presentations method provided predictable and meaningful results. Sentences containing idioms used literally required more presentations than those containing idioms used figuratively. Cued recall was better for idioms used literally than for those used figuratively. These results are interpreted as support for the Idiomatic Processing Model of idiom comprehension, which suggests that the figurative meaning is processed first; only if that one is inappropriate is the literal meaning processed.     

Age-related changes in working and reference memory performance and locomotor activity in the Wistar rat

Wistar rats of three age groups were tested in an automated tunnel-maze system of variable geometry to investigate whether changes in spontaneous locomotor activity and in learning and memory develop differentially or in a correlated fashion as a function of age. Senescent (30 months) as well as mature-adult (17 months) rats showed an age-correlated decline of locomotor activity as compared to the mature-young (5 months) group. Both working-memory (measured as within-trial arm discrimination performance) and reference-memory (measured as avoidance of "blind alley" visits) were severely affected in the senescent group, whereas the middle-aged animals suffered only from a working-memory deficit. The findings provide evidence that locomotor deficits do not necessarily interfere in the assessment of age-related changes in cognitive performance. Furthermore the results support the hypothesis that working and reference memory have different underlying physiological correlates and that these neuronal systems are differentially affected by the aging process.     

Serotonergic and opiate interactions in the modulation of drug- and environmental-induced analgesia in the neonatal rat pup

Serotonergic and opiate interactions in the modulation of drug- and environmental-induced analgesia were assessed in 6-day-old Sprague-Dawley-derived rat pups using tail-flick testing procedures. In these experiments the serotonergic antagonist metergoline was observed to attenuate both the analgesia induced by the opiate agonist morphine and the analgesia induced by isolation from siblings and the dam, an environmental manipulation which has previously been shown to be associated with increases in opiate activity. In contrast, the opiate antagonist naloxone was observed to be ineffective in blocking not only analgesia induced by the serotonergic agonist quipazine, but also analgesia induced by long-term deprivation from the dam and food, a manipulation that has been previously reported to induce increases in serotonergic utilization. These results suggest that in the neonate, as in the adult, the serotonergic modulation of nociception appears to occur "downstream" from the opiate systems serving to regulate nociception following both drug- and environmental-induced alterations in pain sensitivity. Analgesia induced by long-term deprivation from food and the dam appears to be strongly related to increases in serotonergic activity and relatively unaffected by opiate antagonism, whereas analgesia induced by isolation from siblings and the dam may be related to increases in opiate activity, but modulated by serotonergic systems serving to regulate pain responsivity. Thus alterations in the environment, mediated at least in part by alterations in opiate and serotonergic activity, appear to play an important role in influencing the sensitivity of the neonate to pain stimuli.     

From appraisal to emotion: Differences among unpleasant feelings

Recent research has indicated strong relations between people's appraisals of their circumstances and their emotional states. The present study examined these relations across a range of unpleasant situations in which subjects experienced complex emotional blends. Subjects recalled unpleasant experiences from their pasts that were associated with particular appraisals and described their appraisals and emotions during these experiences. Situations defined by particular appraisals along the human agency or situational control dimensions were reliably associated with different levels of anger, sadness, and guilt, as predicted. However, predicted differences in emotion were not observed for situations selected for appraisals along the certainty or attention dimensions. Most subjects reported experiencing blends of two or more emotions, and correlation/regression analyses indicated that even in the context of these blends, patterns of appraisal similar to those observed previously (Smith & Ellsworth, 1985, 1987) characterized the experience of the individual emotions. The regressions further indicated that appraisals along some dimensions were more important to the experience of particular emotions than were appraisals along other dimensions. Thesecentral appraisals are compared with the adaptive functions their associated emotions are believed to serve, and the implications of these findings are discussed.This research was supported in part by a Stanford University graduate fellowship and in part by a National Institute of Mental Health training grant to Craig Smith. Part of the writing was done while Phoebe Ellsworth was a fellow at the Center for Advanced Study in the Behavioral Sciences, supported by the John D. and Catherine T. MacArthur Foundation and by the James McKeen Cattell Fund.     

Comprehension of sentence structure in anomic and conduction aphasia

Picture-pointing auditory and reading comprehension tests were administered to anomic and conduction aphasics. Subjects responded to active sentences of the present progressive form. The possible errors which a subject could make on these experimental tasks included failure to correctly interpret noun order, number, or lexical meaning. Both groups made significantly more correct responses than error responses. Of their error responses, noun-order errors significantly exceeded number and lexical errors for which no differences were observed. When compared with results previously obtained for agrammatic Broca's aphasics, no differences in the pattern of errors were identified. These results are discussed relative to current theories of syntactic processing and for the mechanisms which account for these syntactic comprehension deficits following aphasia.     

Developmental dyslexia and word retrieval deficits

Developmental dyslexics, selected on the basis of very slow naming rates on the Rapid Automatic Naming Tasks (RAN), were compared to normal readers on oral language, picture categorization, and reading tasks. Findings indicated that the dyslexics' word retrieval deficits were one symptom of a more generalized, however subtle, oral language deficit which involved both receptive and expressive oral language functioning. The dyslexics' word retrieval problem also seemed chiefly related to language processing and not to deficits in semantic memory as there were no significant differences between dyslexics and controls on a nonverbal semantic memory task (picture categorization). In naming and identifying printed words, the dyslexics appeared to rely considerably upon the "indirect" or "assembly-of-phonology" route; they were slower in naming irregularly spelled words compared to regularly spelled words and on a lexical decision task, the dyslexics were slower in making negative decisions for "pseudohomophones" (e.g., "braik") than for other matched nonwords. Results are discussed in terms of the logogen model with some consideration of a developmental model as well.     

The foundations of epistemological probability

Epistemological probability is the kind of probability relative to a body of evidence. Many philosophers, including Henry Kyburg and Roderick Chisholm, hold that all epistemological probabilities reflect a relation between an evidential body of propositions and other propositions. But this article argues that some epistemological probabilities for empirical propositions must be relative to non-propositional evidence, specifically the contents of non-propositional perceptual states. In doing so, the article distinguishes between internalism and externalism regarding epistemological probability, and argues for a version of awareness internalism. The article draws three main concluding lessons. First, epistemological probability is not to be identified with the sort of objective, experience-independent probability that is familiar from statistical and propensity interpretations of probability. Second, it is doubtful that epistemological probability is measurable, in any useful way, by real numbers, even if it admits of comparative assessments. Third, contrary to the familiar claim of C. I. Lewis, epistemological probability should not be viewed as requiring a basis of certainty.     

Powers, causation, and modality

A complex theory concerning powers, natures, and causal necessity has emerged from the writings of P. H. Hare, E. H. Madden, and R. Harré. In the course of rebutting objections that other critics have raised to the power account of causation, I correct three of its genuine difficulties: its attempt to analyze power attributions in terms of conditional statements; its characterization of the relation between something's powers and its nature; and its doctrines concerning conceptual necessity. The resulting interpretation of causal modalities is then subsumed under a more general power account of modality, related at a number of points to considerations concerning powers, and further illustrating their philosophical importance.