The influence of selection modality, display dynamics and error feedback on patterns of human foraging.

In a previous series of papers, we have used an iPad task to explore how human participants “forage” through static displays containing multiple targets from two categories. A main finding was that when demands on attention were increased, foraging patterns tended to shift from random category selection to exhaustive category selection. In the current work, we created displays on a vertically oriented touch-screen containing identical target and distractor categories that could either be in motion or at rest. In separate blocks, participants selected target items using different modalities, specifically: a) mouse b) touchscreen or c) infrared hand tracker. Selected targets were always cancelled via a common button press response. Our interest was whether foraging patterns would be the same as those seen with our iPad task. Although the different selection modalities varied considerably in terms of rated familiarity and difficulty of use, they had only a minimal effect on patterns of foraging. There was a very consistent reduction in the number of category switches when attentional load was increased. However, the tendency to use exhaustive runs during high attention conditions was much reduced compared to the iPad task, particularly with dynamic displays. We suggest that this pattern is a consequence of generally slowed response times compared to the iPad task. These findings indicate that in addition to capacity limits, temporal constraints are likely to be an important determinant of foraging patterns in humans. We introduce the term foraging tempo to capture this latter notion and to emphasize the probable role played by the overall pace of the regular, repetitive selections required during multi-target search tasks.