Gaze Scanpath Research Articles

Gaze scan-paths affect recall strategy in context dependent memory.

Gaze scan-paths affect recall strategy in context dependent memory.

Neural Correlates of Subsequent Memory-Related Gaze Reinstatement.

Mounting evidence linking gaze reinstatement-the recapitulation of encoding-related gaze patterns during retrieval-to behavioral measures of memory suggests that eye movements play an important role in mnemonic processing. Yet, the nature of the gaze scanpath, including its informational content and neural correlates, has remained in question. In this study, we examined eye movement and neural data from a recognition memory task to further elucidate the behavioral and neural bases of functional gaze reinstatement. Consistent with previous work, gaze reinstatement during retrieval of freely viewed scene images was greater than chance and predictive of recognition memory performance. Gaze reinstatement was also associated with viewing of informationally salient image regions at encoding, suggesting that scanpaths may encode and contain high-level scene content. At the brain level, gaze reinstatement was predicted by encoding-related activity in the occipital pole and BG, neural regions associated with visual processing and oculomotor control. Finally, cross-voxel brain pattern similarity analysis revealed overlapping subsequent memory and subsequent gaze reinstatement modulation effects in the parahippocampal place area and hippocampus, in addition to the occipital pole and BG. Together, these findings suggest that encoding-related activity in brain regions associated with scene processing, oculomotor control, and memory supports the formation, and subsequent recapitulation, of functional scanpaths. More broadly, these findings lend support to Scanpath Theory's assertion that eye movements both encode, and are themselves embedded in, mnemonic representations.

The Development of Visual Expertise in ECG Interpretation: An Eye-Tracking Augmented Re Situ Interview Approach

Phenomenon: Visual expertise in medicine involves a complex interplay between expert visual behavior patterns and higher-level cognitive processes. Previous studies of visual expertise in medicine have centered around traditionally visually intensive disciplines such as radiology and pathology. However, there is limited study of visual expertise in electrocardiogram (ECG) interpretation, a common clinical task that is associated with high error rates. This qualitatively driven multi-methods study aimed to describe differences in cognitive approaches to ECG interpretation between medical students, emergency medicine (EM) residents, and EM attending physicians. Approach: Ten medical students, 10 EM residents, and 10 EM attending physicians were recruited from one tertiary academic center to participate in this study. Participants interpreted 10 ECGs with a screen-based eye-tracking device, then underwent a subjective re situ interview augmented by playback of the participants’ own gaze scan-paths via eye-tracking. Interviews were transcribed verbatim and an emergent thematic analysis was performed across participant groups. Diagnostic speed, accuracy, and heat maps of fixation distribution were collected to supplement the qualitative findings. Findings: Qualitative analysis demonstrated differences among the cohorts in three major themes: dual-process reasoning, ability to prioritize, and clinical implications. These qualitative findings were aligned with differences in visual behavior demonstrated by heat maps of fixation distribution across each ECG. More experienced participants completed ECG interpretation significantly faster and more accurately than less experienced participants. Insights: The cognitive processes related to ECG interpretation differed between novices and more experienced providers in EM. Understanding the differences in cognitive approaches to ECG interpretation between these groups may help inform best practices in teaching this ubiquitous diagnostic skill.

Modeling sequential context effects in diagnostic interpretation of screening mammograms.

.Prior research has shown that physicians’ medical decisions can be influenced by sequential context, particularly in cases where successive stimuli exhibit similar characteristics when analyzing medical images. This type of systematic error is known to psychophysicists as sequential context effect as it indicates that judgments are influenced by features of and decisions about the preceding case in the sequence of examined cases, rather than being based solely on the peculiarities unique to the present case. We determine if radiologists experience some form of context bias, using screening mammography as the use case. To this end, we explore correlations between previous perceptual behavior and diagnostic decisions and current decisions. We hypothesize that a radiologist’s visual search pattern and diagnostic decisions in previous cases are predictive of the radiologist’s current diagnostic decisions. To test our hypothesis, we tasked 10 radiologists of varied experience to conduct blind reviews of 100 four-view screening mammograms. Eye-tracking data and diagnostic decisions were collected from each radiologist under conditions mimicking clinical practice. Perceptual behavior was quantified using the fractal dimension of gaze scanpath, which was computed using the Minkowski–Bouligand box-counting method. To test the effect of previous behavior and decisions, we conducted a multifactor fixed-effects ANOVA. Further, to examine the predictive value of previous perceptual behavior and decisions, we trained and evaluated a predictive model for radiologists’ current diagnostic decisions. ANOVA tests showed that previous visual behavior, characterized by fractal analysis, previous diagnostic decisions, and image characteristics of previous cases are significant predictors of current diagnostic decisions. Additionally, predictive modeling of diagnostic decisions showed an overall improvement in prediction error when the model is trained on additional information about previous perceptual behavior and diagnostic decisions.

The visual encoding of tool–object affordances

The perception of tool–object pairs involves understanding their action-relationships (affordances). Here, we sought to evaluate how an observer visually encodes tool–object affordances. Eye-movements were recorded as right-handed participants freely viewed static, right-handed, egocentric tool–object images across three contexts: correct (e.g. hammer-nail), incorrect (e.g. hammer-paper), spatial/ambiguous (e.g. hammer-wood), and three grasp-types: no hand, functional grasp-posture (grasp hammer-handle), non-functional/manipulative grasp-posture (grasp hammer-head). There were three areas of interests (AOI): the object (nail), the operant tool-end (hammer-head), the graspable tool-end (hammer-handle). Participants passively evaluated whether tool–object pairs were functionally correct/incorrect. Clustering of gaze scanpaths and AOI weightings grouped conditions into three distinct grasp-specific clusters, especially across correct and spatial tool–object contexts and to a lesser extent within the incorrect tool–object context. The grasp-specific gaze scanpath clusters were reasonably robust to the temporal order of gaze scanpaths. Gaze was therefore automatically primed to grasp-affordances though the task required evaluating tool–object context. Participants also primarily focused on the object and the operant tool-end and sparsely attended to the graspable tool-end, even in images with functional grasp-postures. In fact, in the absence of a grasp, the object was foveally weighted the most, indicative of a possible object-oriented action priming effect wherein the observer may be evaluating how the tool engages on the object. Unlike the functional grasp-posture, the manipulative grasp-posture caused the greatest disruption in the object-oriented priming effect, ostensibly as it does not afford tool–object action due to its non-functional interaction with the operant tool-end that actually engages with the object (e.g., hammer-head to nail). The enhanced attention towards the manipulative grasp-posture may serve to encode grasp-intent. Results here shed new light on how an observer gathers action-information when evaluating static tool–object scenes and reveal how contextual and grasp-specific affordances directly modulate visuospatial attention.

Tracking down the path of memory: eye scanpaths facilitate retrieval of visuospatial information.

Recent research points to a crucial role of eye fixations on the same spatial locations where an item appeared when learned, for the successful retrieval of stored information (e.g., Laeng et al. in Cognition 131:263–283, 2014. doi:10.1016/j.cognition.2014.01.003). However, evidence about whether the specific temporal sequence (i.e., scanpath) of these eye fixations is also relevant for the accuracy of memory remains unclear. In the current study, eye fixations were recorded while looking at a checkerboard-like pattern. In a recognition session (48 h later), animations were shown where each square that formed the pattern was presented one by one, either according to the same, idiosyncratic, temporal sequence in which they were originally viewed by each participant or in a shuffled sequence although the squares were, in both conditions, always in their correct positions. Afterward, participants judged whether they had seen the same pattern before or not. Showing the elements serially according to the original scanpath’s sequence yielded a significantly better recognition performance than the shuffled condition. In a forced fixation condition, where the gaze was maintained on the center of the screen, the advantage of memory accuracy for same versus shuffled scanpaths disappeared. Concluding, gaze scanpaths (i.e., the order of fixations and not simply their positions) are functional to visual memory and physical reenacting of the original, embodied, perception can facilitate retrieval.

Visual scan behavior of new and experienced clinicians assessing panoramic radiographs

ObjectiveThe aim of this study was to examine and compare the visual scan behavior of clinicians with different levels of experience during assessment of panoramic radiographs. MethodsThe visual scan paths of 20 dentists, 10 with 5 years of clinical experience or less (new clinicians) and 10 with more than 5 years of clinical experience (experienced clinicians), were recorded as they assessed five panoramic radiographs. Differences between groups were tested for statistical significance, and associations between level of clinical experience, viewing time, completeness, and detection of abnormality were computed. ResultsExperienced clinicians were significantly quicker (P < 0.001) and, more often than new clinicians, had a discernible scanning pattern. New clinicians often had no pattern to radiograph assessment, but they scanned the radiographs significantly more completely (P < 0.001), and their gaze scan paths entered more areas of abnormality. There were significant positive correlations between viewing time and completeness (P < 0.001), and between viewing time and detection of abnormality (P = 0.042) but not between level of clinical experience and detection of abnormality (P = 0.054). ConclusionsExperienced clinicians have a faster and more systematic approach to panoramic radiograph assessment but tend to be less complete than new clinicians.

Perceptually Based FROC Analysis 1

Analysis of reading data when cases have multiple targets and/or the reader is required to localize targets is difficult. One approach to this free-response operating characteristic (FROC) problem is for images to be segmented (eg, with quadrants) by the investigator and a segment-level analysis be conducted with the case as a nesting factor. In this report, we introduce an alternative method that uses the visual scan path of the reader to segment the image. We evaluate the new method by applying it to data from a mammography reading experiment. The gaze scan path of one radiologist was recorded as she scanned 40 mammograms for masses and microcalcifications. The observer is an experienced mammographer and was not one of the authors. In addition, the reader provided a rating indicating the degree of suspicion for any suspected targets she identified and localized. We then established "perceptual regions" by using a clustering algorithm on the visual fixations. We combined ratings given to specific locations indicated by the reader with the segmentation from the visual scan to generate a series of ratings classified for whether the perceptually based region associated with the rating contained or did not contain a known target. We analyzed data generated by our method from all 40 cases by using the conventional maximum-likelihood method based on the binormal model. Finally, we tested goodness-of-fit of the binormal model to the data by using chi-square. Maximum-likelihood estimation led to a model that did not fit the data (P < .001). However, examination of the observed and expected counts suggests that the binormal assumption does not hold for segments that contain targets and a bimodal distribution model might be preferred. Our new method provides an alternative approach to analysis of the FROC experiment. It needs to be developed further. Specifically, we propose that a mixture model extension of the binormal model be developed for ratings data arising from perceptually based FROC experiments. A disadvantage to our method is the requirement to record the scan path of the reader. However, we believe that adding such information to receiver operating characteristic (ROC) curve analysis will pay off when appropriate statistical models have been identified because we believe our data support our hypothesis that the perceptual scanning of images by humans deconvolves interpretation correlation. If true, this hypothesis implies that conventional statistical methods for ROC analysis based on independent data can be applied to the analysis of FROC data after conditioning on the scan path of the observer.