Integration of information from multiple element displays

This experiment examined the processing of information from multiple element visual displays, using techniques derived from the theory of signal detectability. The method allows one to specify how observers integrate information from individual elements of a display. The experiment tested numerical and graphical displays having different display sizes, durations, and arrangements of elements. Observer performance increased with the number, m, of display elements, but at less than the ideal √m rate. Observer performance was consistent with a model of information integration constrained by internal noise. Linear arrays of elements resulted in better performance than did square arrays. Graphically coded elements resulted in better performance than did numerical elements. Observer decision weighting of element information from graphical displays was approximately uniform across spatial position, but the weighting of information from numerical displays was concentrated on elements near the fixation point.     

The relation of perception and motor action: ideomotor compatibility and interference in divided attention

Ideomotor theory is one variation of the general position that perception and motor action are related. According to this theory, a perceptual representation of the goal of a response must be generated prior to response initiation. Ideomotor theory can be extended by assuming that generation of this representation, which usually is required prior to motor action, is not needed if the stimulus itself corresponds to the response goal, that is, if the stimulus and response are ideomotor compatible. Because processing to generate the response representation is not needed with ideomotor compatibility, it should be possible to control two responses simultaneously without mutual interference if at least one stimulus-response relation is ideomotor compatible. Although supported in previous work involving discrete responses, this prediction of perfect time-sharing was found not to hold in the experiments reported here. These experiments, unlike those showing perfect time-sharing, involved continuous responses. We propose an alternative version of ideomotor compatibility, in which perfect time-sharing can occur if an integrated stimulus is provided to match the continuous and integrated response.     

Improving the retrieval of information from external sources

A major barrier to successful retrieval from external sources (e.g., electronic databases) is the tremendous variability in the words that people use to describe objects of interest. The fact that different authors use different words to describe essentially the same idea means that relevant objects will be missed; conversely, the fact that the same word can be used to refer to many different things means that irrelevant objects will be retrieved. We describe a statistical method called latent semantic indexing, which models the implicit higher order structure in the association of words and objects and improves retrieval performance by up to 30%. Additional large performance improvements of 40% and 67% can be achieved through the use of differential term weighting and iterative retrieval methods.     

Effects of prior juror experience on jury sentencing

The effect of prior juror service on jury sentencing was investigated in an archival study of 143 criminal trials resulting in convictions. Trials took place over two calendar years in a state circuit court requiring jurors to serve 30-day terms. Jurors sentenced defendants in each case according to a set of guidelines determined by trial judges. The severity of the sentences imposed by jurors was rated by 101 subjects on a scale of 1 (least severe) to 100 (most severe). The results indicated that the more experienced juries gave significantly more severe sentences than did the less experienced juries. This finding was unchanged when civil court experience was considered in addition to criminal court experience. Possible interpretations of these results are discussed.     

Adolescents' perceptions of friends' and parents' attitudes to sex and sexual risk-taking

This study investigated the association between adolescents' perceptions of parental and peer attitudes towards sexuality and AIDS precautions, and the risky sexual behaviours of 1008 sexually active, heterosexual undergraduate students aged 17-20 years. Students were asked to rate the extent to which their mothers, fathers and friends would agree or disagree with 16 statements reflecting support of the adolescent engaging in sexual behaviour and using sexual precautions, including precautions against AIDS. The adolescents also indicated whether they were sexually active and their level of condom use in both ‘regular’ (or steady) and ‘casual’ relationships. Results indicated that adolescents perceived their parents as non-liberal in their sexual attitudes and relatively unlikely to discuss sex or precautions with them. Parents were viewed as more accepting of their sons' sexual behaviours than of their daughters'. Adolescents believed that peers were more likely to discuss sexuality and precautions than parents, and were more liberal in their sexual attitudes. Adolescent sexual risk-taking was related to the perceived attitudes of significant others in ways which varied across gender and type of relationship. Implications for interventions are discussed.     

Global-local interference modulated by communication between the hemispheres.

Three experiments examined whether interhemispheric interaction modulates selective attention in a same-different version of D. Navon's (1977) global-local paradigm. In Experiments 1 and 2, interhemispheric interaction reduced interstimulus interference produced when two stimuli matched at a preassigned level (e.g., local) but differed at the irrelevant level (e.g., global). This effect was greater for stimuli made of a few large elements than for those made of many small elements. Experiment 3 demonstrated that (a) the ability of interhemispheric interaction to reduce interstimulus interference is not constrained by hemispheric differences for global and local processing and (b) interhemispheric interaction does not strongly modulate intrastimulus interference produced when the forms at the preassigned (e.g., local) and irrelevant (e.g., global) levels differ within an individual stimulus. These findings indicate that interaction between the hemispheres is a neural mechanism that may aid selective attention.     

A comment on the functional localization of the phonological storage subsystem of working memory.

Working memory, as defined by Baddeley and Hitch, is an interactive set of cognitive processes responsible for holding information online and available for analysis. Part of that system is a specialized subsystem devoted to maintaining verbal information; the verbal "slave" subsystem has as a core component a phonological store. For many years, the anatomical locus of the phonological store has been thought to be in the supramarginal and angular gyri of the speech dominant hemisphere, and functional neuroimaging studies provide broad support for this localization. However, a finer grained analysis of published experiments reveals two possible foci for the phonological store within the parietal lobe, neither of which has a pattern of functional activation that is fully consistent with the Baddeley and Hitch model. The purpose of the present paper is to review several studies relevant to the question of the localization of the phonological store and to suggest possible reasons the results are discrepant.     

Affordance, proper function, and the physical basis of perceived heaviness

The physical basis of perceived heaviness requires consideration of the haptic perceptual system's role in controlling actions (the system's proper function) and the relation of an object's inertial properties to properties of the human movement system (the object's affordance). We show that the mass of a wielded object and particular scalar variables calculated from the object's inertia tensor combine linearly in determining perceived heaviness. The tensor-derived scalars reflect the symmetry and volume of the corresponding inertia ellipsoid. These measures bear directly on the object's wieldability, that is, on the patterning and level of muscular forces required to move the object in a controlled fashion.     

Massage and music therapies attenuate frontal EEG asymmetry in depressed adolescents

EEG asymmetry, specifically greater relative right frontal activation, is associated with negative affect. Depressed adults show stable patterns of this asymmetry. The present study assessed the effects of massage therapy and music therapy on frontal EEG asymmetry in depressed adolescents. Thirty adolescents with greater relative right frontal EEG activation and symptoms of depression were given either massage therapy (n = 14) or music therapy (n = 16). EEG was recorded for three-minute periods before, during, and after therapy. Frontal EEG asymmetry was significantly attenuated during and after the massage and music sessions.