Visual search on a mobile phone display

• Authors: Lauri Repokari;Toni Saarela;Ilmari Kurki
• Venue: SAICSIT '02 Proceedings of the 2002 annual research conference of the South African institute of computer scientists and information technologists on Enablement through technology
• Year: 2002

Information and functions available in mobile phones increaseall the time, but at the same time the size of the phonesdecreases. This leads to a problem of presenting efficiently asmuch information as possible on a small display. Here a visualsearch paradigm was used to measure and compare search times on asmall display with text and icons used as targets. We also studiedthe effect of simultaneously shown icons' features on target iconsearch times. The aim of the study was to compare the search timeson a small display when text or icons are used as targets anddistractors and to further study the effect of different types ofdistractors when using icons. We were also interested to see howsuitable the traditional visual search paradigm is forhuman-computer interaction research.Fifteen subjects (8 women) took part in the experiments.Thirteen icons and thirteen words were used as stimuli. Icons wereacquired from an actual mobile phone user interface. For some ofthe trials, icons were divided into two groups: filled and notfilled. The words used were 5-6 letter Finnish words with the firstletter capitalized. The main results of this study were:1. Visual search is significantly faster on small display whenicons rather than text are used as targets and distractors. Thedifference in search times also increases when the number of itemson the display is increased. With a set size of fifteen, thereaction times were two times greater in text search than in iconsearch.2. Search times can be greatly affected with by choosing theconcurrently shown icons properly.3. Search times in pop-out---search remain on a same leveldespite the size of the set. This result differs from theexpectations in the study based on cognitive psychologyparadigm.The fact that icon search was faster than text search was not initself surprising, because in text search there are always morecharacters on the screen. The results from 'pop-out' ---search showthat effects due to the target-distractor differences, that areknown from basic research, hold in more applied conditions as well.The greatest differences in search times were observed between textand icon search tasks and they were about half a second. This mayseem small at first, but one has to keep in mind that in theseexperiments, subjects had only one task to handle. There is a longway from this to a real life situation, in which the phone is oftenused while simultaneously attending to other, often more demandingtasks as well. One would expect the difference to be even greaterin that kind of situation. Text is naturally always going to play apart in mobile phone interface. Still, it was shown here that theicons are found faster and that the search times can be affected byfeatures of adjacent icons. When designing an interface to asmall-display device, designing and choosing adjacent iconsproperly may help to make the device more efficient to use.