The confirmation and prevalence biases in visual search reflect separate underlying processes

Reward delays quitting in visual search

Reward motivates goal-directed behaviors, leading to faster reaction time (RT) and lower error rate in searching for a target in the reward condition than in the no-reward condition in target-discrimination tasks. However, it is unclear how reward influences target detection in which participants are required to judge whether a predesignated target is present or absent. Here, we asked participants to complete a target-detection search task in which the color of the search array indicated the reward availability of the current trial. Correct and faster (than a baseline) responses would be rewarded if the search array had the reward-related color. In Experiments 1A and 1B, the target was presented in 50% of the trials. Experiment 1B had the same design as Experiment 1A, except that different baselines were set for the target-present and target-absent conditions. In Experiment 2, the proportion of target presence was manipulated to be high (80%), moderate (50%), or low (20%) in different blocks of stimuli. Results showed that, across all the experiments, participants responded faster and made fewer errors in the reward than in the no-reward condition when the target was present. However, this facilitatory effect was reversed when the target was absent, showcasing a reward-induced interference. The signal detection analysis suggested that reward biased the report criterion to the "yes" response. These findings demonstrate that the impact of reward on goal-directed behavior can be detrimental and reward prolongs the search process by rendering participants reluctant to say "no" in visual search termination.

Graded prioritisation of targets in search: reward diminishes the low prevalence effect

In many real-life contexts, observers are required to search for targets that are rarely present (e.g. tumours in X-rays; dangerous items in airport security screenings). Despite the rarity of these items, they are of enormous importance for the health and safety of the public, yet they are easily missed during visual search. This is referred to as the prevalence effect. In the current series of experiments, we investigate whether unequal reward can modulate the prevalence effect, in a multiple target search task. Having first established the impact of prevalence (Experiment 1) and reward (Experiment 2) on how efficiently participants can find one of several targets in the current paradigm, we then combined the two forms of priority to investigate their interaction. An unequal reward distribution (where lower prevalence items are more rewarded; Experiment 3) was found to diminish the effect of prevalence, compared to an equal reward distribution (Experiment 4) as indicated by faster response times and fewer misses. These findings suggest that when combined with an unequal reward distribution, the low prevalence effect can be diminished.

Cue utilisation reduces the impact of response bias in histopathology

Histopathologists make diagnostic decisions that are thought to be based on pattern recognition, likely informed by cue-based associations formed in memory, a process known as cue utilisation. Typically, the cases presented to the histopathologist have already been classified as 'abnormal' by clinical examination and/or other diagnostic tests. This results in a high disease prevalence, the potential for 'abnormality priming', and a response bias leading to false positives on normal cases. This study investigated whether higher cue utilisation is associated with a reduction in positive response bias in the diagnostic decisions of histopathologists. Data were collected from eighty-two histopathologists who completed a series of demographic and experience-related questions and the histopathology edition of the Expert Intensive Skills Evaluation 2.0 (EXPERTise 2.0) to establish behavioural indicators of context-related cue utilisation. They also completed a separate, diagnostic task comprising breast histopathology images where the frequency of abnormality was manipulated to create a high disease prevalence context for diagnostic decisions relating to normal tissue. Participants were assigned to higher or lower cue utilisation groups based on their performance on EXPERTise 2.0. When the effects of experience were controlled, higher cue utilisation was specifically associated with a greater accuracy classifying normal images, recording a lower positive response bias. This study suggests that cue utilisation may play a protective role against response biases in histopathology settings.

Eye movements reflect expertise development in hybrid search

Domain-specific expertise changes the way people perceive, process, and remember information from that domain. This is often observed in visual domains involving skilled searches, such as athletics referees, or professional visual searchers (e.g., security and medical screeners). Although existing research has compared expert to novice performance in visual search, little work has directly documented how accumulating experiences change behavior. A longitudinal approach to studying visual search performance may permit a finer-grained understanding of experience-dependent changes in visual scanning, and the extent to which various cognitive processes are affected by experience. In this study, participants acquired experience by taking part in many experimental sessions over the course of an academic semester. Searchers looked for 20 categories of targets simultaneously (which appeared with unequal frequency), in displays with 0-3 targets present, while having their eye movements recorded. With experience, accuracy increased and response times decreased. Fixation probabilities and durations decreased with increasing experience, but saccade amplitudes and visual span increased. These findings suggest that the behavioral benefits endowed by expertise emerge from oculomotor behaviors that reflect enhanced reliance on memory to guide attention and the ability to process more of the visual field within individual fixations.