On the relationship between peak force and peak force variability in isometric tasks

An experiment is reported documenting the relationship between peak force and peak force variability with a fixed criterion time to peak force for an isometric task requiring activation of the elbow flexors. The results show that maximum peak force increases with increments in time to peak force and that peak force variability increases with increments of peak force in an exponential type function. Furthermore, despite the presence of peak force and time to peak force feedback, subjects systematically shifted time to peak force as a function of the percentage of peak force being produced. This temporal modulation changes the percentage of peak force represented by any given peak force criterion. When peak force is made proportional to the degree of departure from the criterion time to peak force, a linear relationship is found between peak force and peak force variability. These findings suggest that time to peak force and rate of force production are parameters that influence veridical estimates of the force variability function.     

Dysfunctional Attitudes and Suicidal Ideation in Psychiatric Outpatients

To determine if specific sets of dysfunctional attitudes were related to suicidal ideation, the 100-item Dysfunctional Attitude Scale (DAS) was administered to 908 psychiatric outpatients along with the Beck Depression Inventory (BDI), Hopelessness Scale (BHS), Self-Concept Test (BST), and Scale for Suicide Ideation (SSI). The SSI was used to classify the outpatients into 97 (10.7%) suicide ideators and 811 (89.3%) nonideators, and the DAS was scored for nine subscales described by Beck, Brown, Steer, and Weissman (1991) . None of the DAS subscales discriminated the ideators and nonideators or was significantly related to SSI total scores of the suicide ideators after controlling for sex, age, diagnosis of a mood or panic disorder, comorbidity, presence of a personality disorder, a history of a past suicide attempt, the BDI, the BHS, and the BST. The contributions of sets of dysfunctional attitudes for identifying and explaining suicidal ideation were overshadowed by a history of a past suicide attempt and hopelessness.     

How should we question young children's understanding of aspectuality?

In two experiments, we investigated whether 4‐ to 5‐year‐old children's ability to demonstrate their understanding of aspectuality was influenced by how the test question was phrased. In Experiment 1, 60 children chose whether to look or feel to gain information about a hidden object (identifiable by sight or touch). Test questions referred either to the perceptual aspect of the hidden object (e.g., whether it was red or blue), the modality dimension (e.g., what colour it was), or the object's identity (e.g., which one it was). Children who heard the identity question performed worse than those who heard the aspect or dimension question. Further investigation in Experiment 2 (N= 23) established that children's difficulty with the identity question was not due to a problem recalling the objects. We discuss how the results of these methodological investigations impact on researchers’ assessment of the development of aspectuality understanding.