Assessment of parameters of visual attention based on the theory of visual attention (TVA)
To compare visual information processing between the groups we used a computational modelling test method based on Bundesen’s Theory of Visual Attention (TVA)To assess parameters of visual attention we used TVA-based paradigms of whole and partial report. Penning et al.“In TVA-based psychophysical paradigms, participants are briefly presented with letter arrays and instructed to report either all or only specific letters (whole and partial report, respectively). By modelling report accuracy as a function of effective exposure time, researchers can estimate core visual attention parameters (i.e., VPS, visual short-term memory [VSTM] capacity, visual threshold, and top-down control) mathematically independently from each other. Empirical investigationsThe subjects were briefly presented with a series of red and/or blue letters on a PC display. All (whole report) or red (partial report) letters had to be reported. Based on the accuracy of the letter report (dependent variable), different basic parameters determining visual attention performance of a given subject can be estimated.Whole and partial report were carried out in direct succession at both assessments.Subjects completed first the whole report and afterwards the partial report within 60 min. In the whole report the task was to report all presented red and blue letters. The letters were presented for variable exposure durations between 10 and 200 ms (independent variable). In the partial report subjects had to report only the recognized red letters while blue letters served as distractors. The exposure duration was individualized in a pre-test phase to correct for baseline differences (partial report only) aiming for a 70% success rate in identifying at least one letter correctly.Letters were always arranged on a (non-visible) circle around a fixation cross on a 100 Hz-Flatscreen. The subject’s head was fixed in 60cm from the display by a skin rest. Letters were masked in half of the whole report trials and in all partial report trials by a red and a blue shape after presentation in order to delete the contents of the visual bufferBased on maximum likelihood modelling of letter report accuracy at different exposure durations in the whole report, we calculated three parameters of visual processing: Based on the accuracy of letter report in the different partial report conditions, a calculation of spatial laterality TVA parameters were tested for a statistically significant change between initial and final assessment (effect of Time) by paired samples t-test or Wilcoxon signed-rank test. Afterwards, the change of the parameters (