Title page for ETD etd-07022012-113542

Document Type Doctoral Thesis
Author Herold, Marina Patricia
URN etd-07022012-113542
Document Title A comparison of the rate and accuracy of symbol location on visual displays using colour-coded alphabetic and categorisation strategies in Grade 1 to 3 children
Degree PhD
Department Augmentative and Alternative Communication
Advisor Name Title
Prof E Alant Co-Supervisor
Prof C J E Uys Supervisor
  • AK-vertoonontwerp
  • onder-na-bo prosessering
  • bo-na-onder prosessering
  • subkategorisering
  • lokalisering
  • alfabetiese orde
  • akkuraatheid
  • spoed
  • visuele soek
  • rate
  • visual search
  • accuracy
  • location
  • alphabetical order
  • subcategorisation
  • top-down processing
  • bottom-up processing
  • AAC display design
Date 2012-09-01
Availability unrestricted


The ability to locate symbols on a visual display forms an integral part of the effective use of AAC systems. Characteristics of display design and perceptual features of symbols have been shown to influence rate and accuracy of symbol location (Thistle & Wilkinson, 2009; Wilkinson, Carlin, & Jagaroo, 2006). The current study endeavoured to compare the use of two colour-coded organisational strategies (alphabetical order and subcategorisation) for their effectiveness in symbol location and to investigate if some bottom-up features influenced the performance of the participants in these tasks.

114 learners in Grade 1 to 3 in a mainstream school were randomly divided into two groups. Both of the groups were exposed to two visual search tests in alternating order. The tests involved searching for 36 visual targets amongst 81 coloured Picture Communication Symbols on a computer screen in one of two colour-coded organizational methods, namely alphabetical order or subcategorisation. The data from the research task was collected through computer logging of all mouse selections.

Findings showed that locating symbols on a computer screen with a subcategorisation strategy was significantly faster and more accurate than with an alphabetical strategy for the Grade 1 to 3 participants. The differences between the rates and accuracy of target symbol location using the two strategies decreased significantly as grade increased.

It was also found that although the tests in this study placed heavy top-down processing demands on the participants, there was still evidence of bottom-up factors influencing their performance.

Implications for display design in AAC clinical practice were discussed.

2012, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Please cite as follows:

Herold, MP 2012, A comparison of the rate and accuracy of symbol location on visual displays using colour-coded alphabetic and categorisation strategies in Grade 1 to 3 children, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-07022012-113542/ >


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