Comparison of perimeters: Intuitive interference in people who are blind

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Introduction: Difficulties in science and mathematics may stem from intuitive interference of irrelevant salient variables in a task. It has been suggested that such intuitive interference is based on immediate perceptual differences that are often visual. Studies performed with sighted participants have indicated that in the comparison-of-“perimeters” task, “area” was the irrelevant salient variable. Such studies have consistently shown that accuracy is higher and reaction times for correct responses are shorter in congruent trials (no interference of area), than in incongruent trials (interference of area). Methods: Fifteen participants who are blind completed a comparison-of-area and a comparison-of-perimeters tasks, each in a different session. In each comparison trial, the participants explored two tactile geometrical shapes using both hands. To collect the participants’ responses and reaction times, the researchers used a Microsoft Excel Macro file designed for this study. Results: Findings demonstrated that for both rate of correct responses and their reaction times, the performance pattern resembled the one observed previously for sighted participants. In addition, reaction times that were observed there were about five times longer compared to those observed previously for sighted participants. Discussion: These findings indicated that interference of area in comparison to perimeters is evident for participants who are blind. They further suggest that, in mathematics, people who are blind experience interference that had previously been assumed to be tied to visual perception. Implications for practitioners: The study suggests that interference of salient irrelevant variables could cause difficulties in science and mathematics for students who are blind. This knowledge could guide educators and curriculum developers for these students in selecting appropriate learning and instruction methods. In addition, the current findings point to the additional amount of time needed to access graphical information tactilely compared to visually.

Original languageEnglish
Pages (from-to)287-298
Number of pages12
JournalJournal of Visual Impairment and Blindness
Issue number3
StatePublished - 1 May 2018


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