Use of eye tracking in medical education.

Eye tracking has become increasingly applied in medical education research for studying the cognitive processes that occur during the performance of a task, such as image interpretation and surgical skills development. However, analysis and interpretation of the large amount of data obtained by eye tracking can be confusing. In this article, our intention is to clarify the analysis and interpretation of the data obtained from eye tracking. Understanding the relationship between eye tracking metrics (such as gaze, pupil and blink rate) and cognitive processes (such as visual attention, perception, memory and cognitive workload) is essential. The importance of calibration and how the limitations of eye tracking can be overcome is also highlighted.

False memory-guided eye movements: insights from a DRM-Saccade paradigm.

The Deese-Roediger and McDermott (DRM) paradigm and visually guided saccade tasks are both prominent research tools in their own right. This study introduces a novel DRM-Saccade paradigm, merging both methodologies. We used rule-based saccadic eye movements whereby participants were presented with items at test and were asked to make a saccade to the left or right of the item to denote a recognition or non-recognition decision. We measured old/new recognition decisions and saccadic latencies. Experiment 1 used a pro/anti saccade task to a single target. We found slower saccadic latencies for correct rejection of critical lures, but no latency difference between correct recognition of studied items and false recognition of critical lures. Experiment 2 used a two-target saccade task and also measured corrective saccades. Findings corroborated those from Experiment 1. Participants adjusted their initial decisions to increase accurate recognition of studied items and rejection of unrelated lures but there were no such corrections for critical lures. We argue that rapid saccades indicate cognitive processing driven by familiarity thresholds. These occur before slower source-monitoring is able to process any conflict. The DRM-Saccade task could effectively track real-time cognitive resource use during recognition decisions.

The Effects of Placebo and Moderate Dose Alcohol on Attentional Bias, Inhibitory Control and Subjective Craving.

AIMS: Previous research indicates that acute alcohol intoxication and placebo can inhibit people's control over consumption behaviour and heighten attentional bias (AB) towards alcohol-related stimuli and craving. We designed a study to disentangle anticipated from pharmacological effects of alcohol in order to gain a clearer view of their relative contributions to alcohol consumption. METHODS: In a within-participants design (moderate alcohol dose, placebo and control), and over a minimum 2-week period, participants completed a battery of questionnaires and cognitive tasks, followed by a bogus taste task to measure ad libitum consumption. RESULTS: Both alcohol preload and placebo resulted in cognitive and psychological changes, including impaired inhibitory control, heightened AB and craving. However, ad libitum consumption only increased following alcohol and not placebo. Furthermore, inhibitory control impairments did not mediate the relationship between initial intoxication and ad libitum consumption, and findings indicate that increases in craving may mediate this association. CONCLUSION: Psychological processes such as craving may be more important in driving consummatory behaviour relative to transient changes in cognitive processes, such as inhibitory control.

Learning from where 'eye' remotely look or point: Impact on number line estimation error in adults.

In this article, we present an investigation into the use of visual cues during number line estimation and their influence on cognitive processes for reducing number line estimation error. Participants completed a 0-1000 number line estimation task before and after a brief intervention in which they observed static-visual or dynamic-visual cues (control, anchor, gaze cursor, mouse cursor) and also made estimation marks to test effective number-target estimation. Results indicated that a significant pre-test to post-test reduction in estimation error was present for dynamic-visual cues of modelled eye-gaze and mouse cursor. However, there was no significant performance difference between pre- and post-test for the control or static anchor conditions. Findings are discussed in relation to the extent to which anchor points alone are meaningful in promoting successful segmentation of the number line and whether dynamic cues promote the utility of these locations in reducing error through attentional guidance.

What Am I Looking at? Interpreting Dynamic and Static Gaze Displays.

Displays of eye movements may convey information about cognitive processes but require interpretation. We investigated whether participants were able to interpret displays of their own or others' eye movements. In Experiments 1 and 2, participants observed an image under three different viewing instructions. Then they were shown static or dynamic gaze displays and had to judge whether it was their own or someone else's eye movements and what instruction was reflected. Participants were capable of recognizing the instruction reflected in their own and someone else's gaze display. Instruction recognition was better for dynamic displays, and only this condition yielded above chance performance in recognizing the display as one's own or another person's (Experiments 1 and 2). Experiment 3 revealed that order information in the gaze displays facilitated instruction recognition when transitions between fixated regions distinguish one viewing instruction from another. Implications of these findings are discussed.

Social attention in children with epilepsy.

Children with epilepsy may be vulnerable to impaired social attention given the increased risk of neurobehavioural comorbidities. Social attentional orienting and the potential modulatory role of attentional control on the perceptual processing of gaze and emotion cues have not been examined in childhood onset epilepsies. Social attention mechanisms were investigated in patients with epilepsy (n=25) aged 8-18years old and performance compared to healthy controls (n=30). Dynamic gaze and emotion facial stimuli were integrated into an antisaccade eye-tracking paradigm. The time to orient attention and execute a horizontal saccade toward (prosaccade) or away (antisaccade) from a peripheral target measured processing speed of social signals under conditions of low or high attentional control. Patients with epilepsy had impaired processing speed compared to healthy controls under conditions of high attentional control only when gaze and emotions were combined meaningfully to signal motivational intent of approach (happy or anger with a direct gaze) or avoidance (fear or sad with an averted gaze). Group differences were larger in older adolescent patients. Analyses of the discrete gaze emotion combinations found independent effects of epilepsy-related, cognitive and behavioural problems. A delayed disengagement from fearful gaze was also found under low attentional control that was linked to epilepsy developmental factors and was similarly observed in patients with higher reported anxiety problems. Overall, findings indicate increased perceptual processing of developmentally relevant social motivations during increased cognitive control, and the possibility of a persistent fear-related attentional bias. This was not limited to patients with chronic epilepsy, lower IQ or reported behavioural problems and has implications for social and emotional development in individuals with childhood onset epilepsies beyond remission.

"Target-absent" decisions in cancer nodule detection are more efficient than "target-present" decisions!

Many parts of the medical image are never fixated when a radiologist searches for cancer nodules. Experts are able to use peripheral vision very efficiently. The size of the functional visual field appears to increase according to the level of expertise. However, searching a medical image diverges, in a puzzling way, from the typical search for a target feature in the laboratory.

Saccadic Eye Movement Abnormalities in Children with Epilepsy.

Childhood onset epilepsy is associated with disrupted developmental integration of sensorimotor and cognitive functions that contribute to persistent neurobehavioural comorbidities. The role of epilepsy and its treatment on the development of functional integration of motor and cognitive domains is unclear. Oculomotor tasks can probe neurophysiological and neurocognitive mechanisms vulnerable to developmental disruptions by epilepsy-related factors. The study involved 26 patients and 48 typically developing children aged 8-18 years old who performed a prosaccade and an antisaccade task. Analyses compared medicated chronic epilepsy patients and unmedicated controlled epilepsy patients to healthy control children on saccade latency, accuracy and dynamics, errors and correction rate, and express saccades. Patients with medicated chronic epilepsy had impaired and more variable processing speed, reduced accuracy, increased peak velocity and a greater number of inhibitory errors, younger unmedicated patients also showed deficits in error monitoring. Deficits were related to reported behavioural problems in patients. Epilepsy factors were significant predictors of oculomotor functions. An earlier age at onset predicted reduced latency of prosaccades and increased express saccades, and the typical relationship between express saccades and inhibitory errors was absent in chronic patients, indicating a persistent reduction in tonic cortical inhibition and aberrant cortical connectivity. In contrast, onset in later childhood predicted altered antisaccade dynamics indicating disrupted neurotransmission in frontoparietal and oculomotor networks with greater demand on inhibitory control. The observed saccadic abnormalities are consistent with a dysmaturation of subcortical-cortical functional connectivity and aberrant neurotransmission. Eye movements could be used to monitor the impact of epilepsy on neurocognitive development and help assess the risk for poor neurobehavioural outcomes.

Worth a quick look? Initial scene previews can guide eye movements as a function of domain-specific expertise but can also have unforeseen costs.

Rapid scene recognition is a global visual process we can all exploit to guide search. This ability is thought to underpin expertise in medical image perception yet there is no direct evidence that isolates the expertise-specific contribution of processing scene previews on subsequent eye movement performance. We used the flash-preview moving window paradigm (Castelhano & Henderson, 2007) to investigate this issue. Expert radiologists and novice observers underwent 2 experiments whereby participants viewed a 250-ms scene preview or a mask before searching for a target. Observers looked for everyday objects from real-world scenes (Experiment 1), and searched for lung nodules from medical images (Experiment 2). Both expertise groups exploited the brief preview of the upcoming scene to more efficiently guide windowed search in Experiment 1, but there was only a weak effect of domain-specific expertise in Experiment 2, with experts showing small improvements in search metrics with scene previews. Expert diagnostic performance was better than novices in all conditions but was not contingent on seeing the scene preview, and scene preview actually impaired novice diagnostic performance. Experiment 3 required novice and experienced observers to search for a variety of abnormalities from different medical images. Rather than maximizing the expertise-specific advantage of processing scene previews, both novices and experienced radiographers were worse at detecting abnormalities with scene previews. We discuss how restricting access to the initial glimpse can be compensated for by subsequent search and discovery processing, but there can still be costs in integrating a fleeting glimpse of a medical scene. (PsycINFO Database Record

Visual information search in simulated junction negotiation: gaze transitions of young novice, young experienced and older experienced drivers.

INTRODUCTION: Older drivers and young novice drivers have problems negotiating road junctions. Explanations for problems largely focus on limitations in visual information processing and observation errors associated with age and experience. METHOD: Gaze transitions provide information on the positional relationship of fixations, providing a useful tool for highlighting gaps in driver's visual information acquisition strategies. The gaze transitions of three driver groups (young novice, young experienced, and older experienced) were compared during gap selection in right turn junction negotiation manoeuvres. RESULTS: When scanning the junction, young experienced drivers distributed their gaze more evenly across all areas, whereas older and novice drivers made more sweeping transitions, bypassing adjacent areas. The use of a preview strategy in the decision phase was less evident in the older experienced group compared to the younger groups. IMPACT: The application of results to driver training interventions and future research are discussed.

Negative priming for target selection with saccadic eye movements.

We conducted a series of experiments to determine whether negative priming is used in the process of target selection for a saccadic eye movement. The key questions addressed the circumstances in which the negative priming of an object takes place, and the distinction between spatial and object-based effects. Experiment 1 revealed that after fixating a target (cricket ball) amongst an array of semantically related distracters, saccadic eye movements in a subsequent display were faster to the target than to the distracters or new objects, irrespective of location. The main finding was that of the facilitation of a recent target, not the inhibition of a recent distracter or location. Experiment 2 replicated this finding by using silhouettes of objects for selection that is based on feature shape. Error rates were associated with distracters with high target-shape similarity; therefore, Experiment 3 presented silhouettes of animals using distracters with low target-shape similarity. The pattern of results was similar to that of Experiment 2, with clear evidence of target facilitation rather than the inhibition of distracters. Experiment 4 and 5 introduced a distracter together with the target into the probe display, to generate a level of competitive selection in the probe condition. In these circumstances, clear evidence of spatial inhibition at the location of the previous distracters emerged. We discuss the implications for our understanding of selective attention and consider why it is essential to supplement response time data with the analysis of eye movement behaviour in spatial negative priming paradigms.

Using another's gaze as an explicit aid to insight problem solving.

Research has shown that implicitly guiding attention via visual cues or unrelated tasks can increase the likelihood of solving insight problems. We examined whether following another person making specific skin-crossing saccades could induce similar attentional shifts and increase solution rates for Duncker's ((1945)) radiation problem. We presented 150 participants with one of three 30-s eye movement patterns from another problem solver: (a) focusing solely on the central tumour; (b) naturally making skin-crossing saccades between the outside area and the tumour from multiple angles; or (c) making deliberate skin-crossing saccades between the outside area and the tumour from multiple angles. Following another person making skin-crossing saccades increased the likelihood of solving the radiation problem. Our results demonstrate that another person's eye movements can promote attentional shifts that trigger insight problem solving.

Viewing another person's eye movements improves identification of pulmonary nodules in chest x-ray inspection.

Double reading of chest x-rays is often used to ensure that fewer abnormalities are missed, but very little is known about how the search behavior of others affects observer performance. A series of experiments investigated whether radiographers benefit from knowing where another person looked for pulmonary nodules, and whether the expertise of the model providing the search behavior was a contributing factor. Experiment 1 compared the diagnostic performance of novice and experienced radiographers examining chest x-rays and found that both groups performed better when shown the search behavior of either a novice radiographer or an expert radiologist. Experiment 2 established that benefits in performance only arose when the eye movements shown were related to the search for nodules; however, only the novices' diagnostic performance consistently improved when shown the expert's search behavior. Experiment 3 reexamined the contribution of task, image, and the expertise of the model underlying this benefit. Consistent with Experiment 1, novice radiographers were better at identifying nodules when shown either a naïve's search behavior or an expert radiologist's search behavior, but they demonstrated no improvement when shown a naïve model not searching for nodules. Our results suggest that although the benefits of this form of attentional guidance may be short-lived, novices can scaffold their decisions based on the search behavior of others.