Systat, but while the one studying air traffic controllers said that he rarely used it for anything more than basic description, his opposite number concerned with motorway emergency management brought out analyses across most of the range of which the package is capable. As with most knowledge, there are few if any


impermeable membranes separating results of psychological research. What inclines someone to be an aggressive driver, for instance, may well influence their likelihood of aggression in other areas too. Several researchers I spoke to were working within, or in association with, police forces and however diverse their areas of study, their measures and methods were very similar. Sonja, funded by a north European law


enforcement agency to study the psychological indicators of adolescents who do and do not join nascent gang cultures, finds many areas of overlap with the aggressive driving researchers. So does Anton who, further east, tries through analysis of recorded custody interviews, to make statistical sense of psychological patterns in racial and religious violence. Sonja and Anton exchange data and findings with one another on an unofficial ad hoc level; one runs intensive batch processing in R, the other in Statistica,


Psyching out the data


Leland Wilkinson, originator of the Systat data analysis and visualisation software, and of Java analytical graphics foundation nVIZn, has long and variously argued that graphical data visualisations need to be conceived and designed within a transactional grammar shaped by the psychology of human perception. ‘We map in order to organise our world in our mind,’ saysWilkinson[14]


, ‘...abstract reasoning


is built on metaphors for reality.’ He has devoted a significant proportion of his career to developing visualisation techniques founded on this approach, strongly influencing statistical graphics thinking in general. Compared to its market sector as a whole, Systat contains a very high proportion of plotting methods based on psychoperceptual principles, pulling in those developed by others as well as by Wilkinson himself. He has recently launched a new exploratory system built on his precepts. The use of psychological thinking, whether explicit or implicit, in designing data communication is of course older than scientific computing. Wilkinson mentions[14]


Charles Joseph


Minard’s compound graphic illustrating French losses in the 1812-1813 Russian campaign, and Florence Nightingale’s use of polar area ‘rose diagrams’ in the 1850s is another well-known example. Nevertheless, it is the use of scientific


12 SCIENTIFIC COMPUTING WORLD


computing methods that has allowed this approach to flower as a widespread means of data analytic communication. The most visible current expression of this is in journalistic encapsulation of complex situations by broadsheets, television news and websites – Guardian Data being a well-known user. Tableau Software, whose frequent recruitment advertisements for psychology graduates are a clear indicator of their approach, are behind many well-known examples of this trend, providing both commercial and no cost software with web platforms upon which the results can be placed. Drag and drop variables entry, multiple views onto the same data, sophisticated data brushing to provide simultaneous subsetting in all of those views and use of multiple modalities all play to the inherent mapping faculties of human psychology. ‘Colour is a great way to encode categorical data for visual analysis because the human visual system can isolate marks for visual comparison,’ comments Jock McKinley, director of Visual Analysis at Tableau. ‘However, as number of categories grows, the colours can become similar, which makes it hard for the visual system to isolate a specific colour... [and]... we recommend that you encode the data with shape... perceptual best practices like these help people to achieve speed-of-thought analysis.’


and there is a language barrier but they use SigmaPlot as a lingua franca and enthuse about the synergistic value of the collaboration. Moving back a little from such concrete


concerns to more fundamental quests for understanding, and also a little way into the borderlands of neurobiology, a study of emotional response by Martin Klasen (University of Aachen) and others[9]


also


illustrates multiple scientific computing roles in experimental psychology. Studying the supramodal representation of


emotion, Klasen used virtual reality technology (thus avoiding the difficulty for a human actor of trying to present incongruent signal combinations) to generate avatars displaying a range of facial expressions representing different emotional states. Spoken disyllabic pseudo words with the patterns of stress and intonation corresponding to similar states were lip synchronised to the avatars, sometimes congruently and sometimes not (48 combinations in each case) in a block experimental design mixing audio, visual and audio-visual versions. Respondents were asked to quickly classify the results across nearly 400 individual trials.


Congruent (warm colours) versus incongruent (cold colours) emotion. Incongruent trials activated a widespread frontoparietal network, cerebellum, and bilateral caudate nucleus. Congruent emotions activated insula and a temporoparietal network along with bilateral amygdala. Insets show blood oxygen level dependent signal changes to happy (yellow), angry (red), neutral (blue) and incongruent (green) audio-visual trials. Illustration from Klasen et al[9]


From analysed functional magnetic resonance


imaging (fMRI) scans, a multiple predictor random-effects general linear model was then used to generate statistical parametric maps according to stimulus type. Mean testing and repeated-measures ANOVA testing were applied to the response data alongside conjunctional analysis of the fMRI results. Te outcome, cutting to the chase, was a strong indication that visual and audible signals are emotionally integrated late in the limbic system’s soſtware processing rather than at the perceptual level. One of my pre-university correspondents,


prompted by experience of juggling exams and the 24-hours-a-day demands of a young baby, is conducting an impressively rigorous piece of primary research on sleep deprivation in adolescent parents, running data analyses in Mystat, the free student version of Systat. Sleep deprivation seems to be associated


in most people’s minds with deliberate use as a dislocator in interrogation, but is in reality widespread as a result and cause of medical problems across the general population. Te mechanisms are sometimes purely physical but far more oſten psychological or psychosomatic; they are highlighted for instance in a report[10]


holistic approaches to critical care. A paper[11]


published in the British Medical


Journal earlier this year illustrates the vicious circle. Patients recovering from surgical intervention in a life-threatening condition suffer depression and anxiety; this disrupts sleep; loss of sleep leads to pain, fatigue and reduced


www.scientific-computing.com


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