Why a Diagram is (Sometimes) Worth Ten Thousand Words

We distinguish diagrammatic from sentential paper-and-pencil representations of information by developing alternative models of information-processing systems that are informationally equivalent and that can be characterized as sentential or diagrammatic. Sentential representations are sequential, like the propositions in a text. Diagrammatic representations are indexed by location in a plane. Diagrammatic representations also typically display information that is only implicit in sentential representations and that therefore has to be computed, sometimes at great cost, to make it explicit for use. We then contrast the computational efficiency of these representations for solving several illustrative problems in mathematics and physics. When two representations are informationally equivalent, their computational efficiency depends on the information-processing operators that act on them. Two sets of operators may differ in their capabilities for recognizing patterns, in the inferences they can carry out directly, and in their control strategies (in particular, the control of search). Diagrammatic and sentential representations support operators that differ in all of these respects. Operators working on one representation may recognize features readily or make inferences directly that are difficult to realize in the other representation. Most important, however, are differences in the efficiency of search for information and in the explicitness of information. In the representations we call diagrammatic, information is organized by location, and often much of the information needed to make an inference is present and explicit at a single location. In addition, cues to the next logical step in the problem may be present at an adjacent location. Therefore problem solving can proceed through a smooth traversal of the diagram, and may require very little search or computation of elements that had been implicit.     

Stability and change in children's skill

Summary This paper explores age-related performance variability, both within trials and between sessions, in repetitive hopping. The mean, the standard deviation (SD), and the coefficient of variation (CV) of several timing and ground-reaction-force variables of hopping were analysed by repeated-measures ANOVA for age-related effects across test sessions and foot used. Forty-five subjects in five age groups (3–4 years, 4–5 years, 6–7 years, 8–9 years, or Adult) performed self-paced, one-footed hopping on three occasions within one week. As was expected, the results showed main effects for Age in all force and time variables, with the exception of CV of medio-lateral force. No significant main effects for Feet were revealed. However, significant Feet x Session interactions were found in flight-time measures, with higher flight-time SD and lower CV for the non-preferred foot in Session 1, a reversal in Session 2, and a negligible difference in Session 3. Across sessions, decreased SD and CV for both vertical and medio-lateral force and shorter flight time indicated more efficient hopping. Overall, it was concluded that SD and CV measures were more sensitive measures of children's performance across repeated sessions than were mean scores and that the order of testing the limbs is an important consideration in experimental protocols when lateralized tasks are measured.     

Partial masking in electrocutaneous sensation: a model for sensation matching, with applications to loudness recruitment

A model for partial masking and other threshold-elevation effects is presented in the context of a sensation-matching paradigm. The model is applied to an electrocutaneous experiment in which the subjects adjusted stimulus intensity on the right-hand fingertip to match sensation levels of standard stimuli presented to the left fingertip. Concurrent mechanical stimulation on the right fingertip masked sensation magnitude in a way consistent with the model. Similarities between this tactile masking effect and analogous auditory phenomena are explored. When applied to loudness matching, the model describes the general shape of loudness contours and it shows that the steep slopes observed in auditory masking and "recruitment" can be a consequence of a threshold shift alone, without a supranormal growth in loudness. The model also shows that a small response bias can distort plots of sensation matching, leading to the suggestion that some varieties of loudness recruitment may not have a sensory basis.     

Reliability and validity of the self‐perception profile for adolescents: An Australian sample

In this study, we explored the psychometric properties and factorial validity of Harter's Self‐Perception Profile for Adolescents (SPPA) with an Australian sample drawn from the Raine study 14‐year follow‐up. Participants, boys (n = 795) and girls (n = 758) from Grades 8, 9, and 10, completed the SPPA. Cronbach's alpha showed good internal reliabilities for seven of the eight subscales and global self‐worth. Boys had significantly higher athletic (p < .001), physical appearance (p < .001), and romantic (p < .05) self‐perceptions, while the girls perceived significantly higher behavioural conduct (p < .001) and close friendships (p < .001). Exploratory factor analysis yielded similar factors to those reported by Harter with North American adolescents, although cross loadings resulted in one additional factor. Our findings generally supported Harter's conceptualisation of the self as a multidimensional construct, and with minor modifications, the use of the SPPA with Australian adolescents.     

Experimenter Effects on Cardiovascular Reactivity and Task Performance During Mental Stress Testing

The Psychological Record - Experimenter effects have long been hypothesized to influence participants’ responses to mental stress testing. To explore the influence of experimenter warmth on...     

Books briefly noted

The Panopticon Writings By Jeremy Bentham (Edited by Miran Bo?ovic, Verso, 1995. ISBN 1–85984–958‐X (hbk) £34.95.

The Other Side of Language: A Philosophy of Listening By Gemma Corradi Fiumara, Routledge, 1995, Pp. 231. ISBN 0–415–04927‐X. £12.99.

Foreign Bodies By Alphonso Lingis, Routledge, 1994, Pp. vii + 236. ISBN 0–415–90990–2. £45.00 (hbk), £15.99 (pbk)     

The effects of leader gender on self-presentational concerns in exercise

The present study examined the impact of the exercise leader's gender on the self-presentational concerns of women in a live exercise class. Eighty-seven college-aged non- or infrequent exercisers participated in a group exercise class led by either a female or male instructor. Participants completed measures of Self-Presentational Efficacy (SPE), State Social Anxiety (SSA) and State Social Physique Anxiety (SPA-S) prior to and following completion of a group exercise class. A repeated measures Multivariate Analysis of Variance (MANOVA), with time as the within-subjects factor and leader gender as the between-subjects factor, was conducted. A significant main effect for time was found (F(3, 80) = 19.65, p < 0.001). Estimated marginal means indicated that all participants reported significantly higher SPE and lower SSA and SPA-S post-exercise. Completing an exercise class may override any self-presentational concerns that can arise from the exercise environment. Future studies should adopt ecologically valid research designs to gain a clearer picture of self-presentational concerns in exercise classes.     

Central synaptic mechanisms underlie short-term olfactory habituation in Drosophila larvae

Naive Drosophila larvae show vigorous chemotaxis toward many odorants including ethyl acetate (EA). Chemotaxis toward EA is substantially reduced after a 5-min pre-exposure to the odorant and recovers with a half-time of ～20 min. An analogous behavioral decrement can be induced without odorant-receptor activation through channelrhodopsin-based, direct photoexcitation of odorant sensory neurons (OSNs). The neural mechanism of short-term habituation (STH) requires the (1) rutabaga adenylate cyclase; (2) transmitter release from predominantly GABAergic local interneurons (LNs); (3) GABA-A receptor function in projection neurons (PNs) that receive excitatory inputs from OSNs; and (4) NMDA-receptor function in PNs. These features of STH cannot be explained by simple sensory adaptation and, instead, point to plasticity of olfactory synapses in the antennal lobe as the underlying mechanism. Our observations suggest a model in which NMDAR-dependent depression of the OSN-PN synapse and/or NMDAR-dependent facilitation of inhibitory transmission from LNs to PNs contributes substantially to short-term habituation.     

CD4 Count and Physical Symptoms Among Urban African American Mothers with HIV: An Examination of the Role of Optimism and Depressive Symptoms

The current study examined the link between immune functioning (CD4 count) and physical symptoms, as well as the moderating role of optimism and depressive symptoms, in a sample of 99 low income, inner city African American women with HIV. Although there was no main effect of CD4 count on physical symptoms, depressive symptoms moderated the association between CD4 count and physical symptoms. More compromised immune functioning (lower CD4 count) was associated with more physical symptoms under conditions of higher levels of depressive symptoms, but not lower levels of depressive symptoms. This finding was observed using both a self-report measure and a clinician-rating of women’s depressive symptoms. There were no main or interactive effects for optimism. Clinical implications and future research directions are presented.