Department of Psychological and Brain Sciences, The George Washington University, Washington, DC, USA.
Cogn Res Princ Implic. 2021 Mar 19;6(1):19. doi: 10.1186/s41235-021-00286-1.
Professions such as radiology and aviation security screening that rely on visual search-the act of looking for targets among distractors-often cannot provide operators immediate feedback, which can create situations where performance may be largely driven by the searchers' own expectations. For example, if searchers do not expect relatively hard-to-spot targets to be present in a given search, they may find easy-to-spot targets but systematically quit searching before finding more difficult ones. Without feedback, searchers can create self-fulfilling prophecies where they incorrectly reinforce initial biases (e.g., first assuming and then, perhaps wrongly, concluding hard-to-spot targets are rare). In the current study, two groups of searchers completed an identical visual search task but with just a single difference in their initial task instructions before the experiment started; those in the "high-expectation" condition were told that each trial could have one or two targets present (i.e., correctly implying no target-absent trials) and those in the "low-expectation" condition were told that each trial would have up to two targets (i.e., incorrectly implying there could be target-absent trials). Compared to the high-expectation group, the low-expectation group had a lower hit rate, lower false alarm rate and quit trials more quickly, consistent with a lower quitting threshold (i.e., performing less exhaustive searches) and a potentially higher target-present decision criterion. The expectation effect was present from the start and remained across the experiment-despite exposure to the same true distribution of targets, the groups' performances remained divergent, primarily driven by the different subjective experiences caused by each groups' self-fulfilling prophecies. The effects were limited to the single-targets trials, which provides insights into the mechanisms affected by the initial expectations set by the instructions. In sum, initial expectations can have dramatic influences-searchers who do not expect to find a target, are less likely to find a target as they are more likely to quit searching earlier.
放射学和航空安全检查等职业依赖于视觉搜索，即从干扰项中寻找目标的行为。通常情况下，这些职业无法为操作人员提供即时反馈，这可能导致绩效在很大程度上取决于搜索者自身的期望。例如，如果搜索者不期望在特定搜索中出现相对难以发现的目标，他们可能会发现容易发现的目标，但在找到更难的目标之前，他们可能会系统地停止搜索。没有反馈，搜索者可能会产生自我实现的预言，即他们错误地强化了最初的偏见（例如，先假设，然后可能错误地得出难以发现的目标很少的结论）。在当前的研究中，两组搜索者完成了相同的视觉搜索任务，但在实验开始前，他们的初始任务指令只有一个细微的区别；在“高期望”条件下，告诉搜索者每个试验可能有一个或两个目标（即正确地暗示没有目标缺失的试验），而在“低期望”条件下，告诉搜索者每个试验最多有两个目标（即错误地暗示可能有目标缺失的试验）。与高期望组相比，低期望组的命中率较低，虚报率较低，退出试验更快，这与较低的退出阈值（即进行较少的详尽搜索）和潜在较高的目标存在决策标准相一致。期望效应从一开始就存在，并在整个实验中持续存在——尽管两组都暴露在相同的目标真实分布下，但其表现仍然存在分歧，主要是由两组的自我实现预言所导致的不同主观体验驱动的。这种影响仅限于单一目标的试验，这为理解由指令设定的初始期望所影响的机制提供了线索。总之，最初的期望会产生显著的影响——那些不期望找到目标的搜索者，由于更有可能更早停止搜索，因此找到目标的可能性较小。
