Abstract
Various conditions of real-world visual search may impact search performance and perceived difficulty. Given the necessity of accurate target detection across professions, this study explored the conditions in which visual search performance and perceived task difficulty may be affected. Conditions varied between a dynamic (continuous horizontal scroll) or static display, a high or low (50% or 10%) target prevalence, and a fast or slow (3.5 or 7 second) display speed. Participants (n = 563), recruited through Amazon Mechanical Turk (MTurk), were randomly distributed across eight conditions of visual search and tasked with determining the presence of known targets, “T”s, amongst a display of distractors, offset “L”s (stimuli from Peltier & Becker, 2015), as well as rating their perceived work load via the NASA Task Load Index (NASA-TLX). Low target prevalence and faster display speed reduced hit rate, while display type did not produce a significant effect on hit rate. Responses to the NASA-TLX indicate that participants rated lower target prevalence as less physically demanding, faster display speed as more temporally demanding, and, notably, dynamic displays as less effortful, less mentally demanding, and less temporally demanding. The finding that participants deemed the dynamic display as less effortful could be attributed to the condition’s predictable item movement and target onset location within the display (Alvarez, Konkle, & Oliva, 2007). This explanation is supported by previous research demonstrating that predictable item movement improves search efficiency through the reduction of necessary eye movements (Boot, Becic, & Kramer, 2009), while unpredictable item movement has been shown to decrease search efficiency and accuracy (Peltier & Becker, 2015). Considering the current study’s results in-conjunction with previous research, we postulate that predictable item movement reduces the need for eye movements, decreasing the perceived difficulty of the visual search and potentially improving efficiency.