What Versus How in Visual Search: Effects of Object Recognition Training, Strategy Training, and Non-invasive Brain Stimulation on Satellite Image Search

Abstract

Visual search is required in many professions where an undetected threat, such as a weapon, can put the well-being of others at risk. Given the importance of detecting these threats, researchers have used various experimental techniques to improve performance in visual search tasks, albeit with varying degrees of success. Here, we explore two promising techniques to improve visual search using ecologically valid synthetic aperture radar stimuli: object recognition training and search strategy training. Search strategy training is intended to make observers search more systematically through a display, whereas object recognition training is intended to improve observers’ ability to recognize critical targets. Search strategy training was implemented by instructing participants to scan through the display in a pre-specified pattern. Object recognition training was implemented by having participants discriminate between targets and non-targets. We also manipulated whether observers received anodal or sham transcranial direct current stimulation (tDCS) during training, which has been shown to improve visual search performance and target learning. To measure the effectiveness of the training and stimulation conditions, we tested object recognition accuracy and overall visual search performance before and after three sessions of increasingly difficult training. Results indicated that object recognition training significantly improved object recognition accuracy relative to the search strategy group, whereas search strategy training was effective in improving visual search accuracy in those who adhered to the training. However, tDCS did not interact with training type, and although both training types yielded significant improvements, training-related improvements were not significantly different between the different approaches. This evidence suggests that strategy-based training could be as effective as the more prototypical object recognition training. Implications for future training protocols are discussed.