Comparing Haptic Pattern Matching on Tablets and Phones: Large Screens Are Not Necessarily Better.

Touchscreen-based, multimodal graphics represent an area of increasing research in digital access for individuals with blindness or visual impairments; yet, little empirical research on the effects of screen size on graphical exploration exists. This work probes if and when more screen area is necessary in supporting a pattern-matching task.

PURPOSE: Larger touchscreens are thought to have distinct benefit over smaller touchscreens for the amount of space available to convey graphical information nonvisually. The current study investigates two questions: (1) Do screen size and grid density impact a user's accuracy on pattern-matching tasks? (2) Do screen size and grid density impact a user's time on task?

METHODS: Fourteen blind and visually impaired individuals were given a pattern-matching task to complete on either a 10.5-in tablet or a 5.1-in phone. The patterns consisted of five vibrating targets imposed on sonified grids that varied in density (higher density = more grid squares). At test, participants compared the touchscreen pattern with a group of physical, embossed patterns and selected the matching pattern. Participants were evaluated on time exploring the pattern on the device and their pattern-matching accuracy. Multiple and logistic regressions were performed on the data.

RESULTS: Device size, grid density, and age had no statistically significant effects on the model of pattern-matching accuracy. However, device size, grid density, and age had significant effects on the model for grid exploration. Using the phone, exploring low-density grids, and being older were indicative of faster exploration time.

CONCLUSIONS: A trade-off of time and accuracy exists between devices that seems to be task dependent. Users may find a tablet most useful in situations where the accuracy of graphic interpretation is important and is not limited by time. Smaller screen sizes afforded comparable accuracy performance to tablets and were faster to explore overall.