Algorithms for randomness in the behavioral sciences: A tutorial

Brysbaert, Marc

doi:10.3758/bf03203334

Cited by 45 publications

(35 citation statements)

References 28 publications

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“…They were told to fixate a gap between two vertically aligned lines in the middle of the screen. In order to ensure adequate fixation, at a random time interval [ 13 ], a digit between 0 and 9 was presented between the fixation lines for 40 ms followed by a mask ( ), instead of a word. Subjects had to identify the digit and were warned by a tone if they made a mistake.…”

Section: Methodsmentioning

confidence: 99%

Interhemispheric transfer and the processing of foveally presented stimuli

Brysbaert

1994

Behavioural Brain Research

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169

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Two arguments are commonly given in favor of a nasotemporal overlap along the vertical meridian of the visual field: anatomical findings and the existence of macular sparing in hemianopia. A review of the literature, however, points to the weakness of the evidence. The anatomical indications are exclusively based on horseradish peroxidase studies, which can not give an unequivocal answer to the amount of overlap in central vision, and which were not supported by a recent study that made use of the more direct ["C]2deoxy-D-glucose technique. The argument of macular sparing in hemianopia appears to be derived evidence that depends on the validity of the anatomical findings. In addition, behavioral studies consistently failed to find functional confirmation of the overlap. To further test the possibility of bilateral representation in central vision, a new paradigm is proposed. It is argued that if interhemispheric transfer is needed for the processing of foveally presented stimuli, the word-beginning superiority effect should be larger for subjects with left hemisphere dominance than for subjects with right hemisphere dominance. Results are in line with the hypothesis and point to the fact that interhemispheric transfer of visual information may be involved in more processing than usually accepted. It is also noted that transfer time seems to depend on the amount of information that must be transferred, and is significantly shorter than the estimates obtained in visual half field studies.Key words: Corpus callosum; Interhemispheric transfer; Macular sparing; Foveal vision; Optimal viewing position; Visual half field studies vision in the foveal region, a phenomenon called macular or foveal sparing. I will discuss the two arguments successively. Anatomical evidence of a hemiretinal overlapThe anatomical evidence for an overlap between the nasal and the temporal hemiretina comes from studies of unilateral sectioning of the optic tract or unilateral electrophoretic injection of horseradish peroxidase (HRP) into the dorsal lateral geniculate nucleus (dLGN) [ 19,20,35,36,52,53,55]. This technique allows tracing the ganglion cells of the retina which project to the dLGN and from there to the visual cortex. The general finding is that in a strip of about 0.2 mm along the vertical midline, ipsilaterally and contralaterally projecting ganglion cells intermingle. This is true both for cats and monkeys. According to Leventhal et al. [35,36] the overlap is primarily due to the presence of ipsilaterally projecting cells in the nasal hemiretina, rather than to contralaterally projecting cells in the temporal hemiretina. Interhemispheric transfer and the processing of foveally presented stimuliDue to the partial decussation of the optic nerves at the optic chiasm, the human visual field is split in two halves: the left and the right visual field (LVF and RVF). Both hemifields project to the contralateral cerebral hemisphere. That is, stimuli presented in the LVF are transmitted to the right cerebral hemisphere, and stimu...

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Section: Methodsmentioning

confidence: 99%

Interhemispheric transfer and the processing of foveally presented stimuli

Brysbaert

1994

Behavioural Brain Research

Self Cite

124

169

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“…However, the uniform deviates generated in the SPSS program are converted to standard normal deviates using the Box-Muller algorithm (see Brysbaert, 1991, and the COMPUTE x = statement in Appendix C).…”

Section: Parallel Analysismentioning

confidence: 99%

SPSS and SAS programs for determining the number of components using parallel analysis and Velicer’s MAP test

O’Connor

2000

Behavior Research Methods, Instruments, & Computers

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2,137

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“…Tscope contains a C implementation of the randomizers described by Brysbaert (1991). With these randomizers, random values can be drawn from uniform, normal, or exponential distributions.…”

Section: Functionality Provided By Tscopementioning

confidence: 99%