Focal lung pathology detection in radiology: Is there an effect of experience on visual search behavior?

In radiology, 60% to 80% of diagnostic errors are perceptual. The use of more efficient visual search behaviors is expected to reduce these errors. We collected eye-tracking data from participants with different levels of experience when interpreting chest X-rays during the completion of a pathology-detection task. Eye-tracking measures were assessed in the context of three existing visual search theories from the literature to understand the association between visual search behavior and underlying processes: the long-term working memory theory, the information-reduction hypothesis, and the holistic model of image perception. The most experienced participants (radiology residents) showed the highest level of performance, albeit their visual search behaviors did not differ from the intermediate group. This suggests that radiology residents better processed the represented information on the X-ray, using a visual search strategy similar to the intermediate group. Since similar visual search resulted in more information extraction in the radiology residents compared with the intermediates, we suggest that this result might support the long-term working memory theory. Furthermore, compared with novices, intermediates and radiology residents fixated longer on areas that were more important to avoid missing any pathology, which possibly confirms the information-reduction hypothesis. Finally, the larger distances between fixations observed in more experienced participants could support the holistic model of image perception. In addition, measures of generic skills were related to a lower time cost for switching between global and local information processing. Our findings suggest that the three theories may be complementary in chest X-ray interpretation. Therefore, a unified theory explaining perceptual-cognitive superiority in radiology is considered.

     

The influence of depth segmentation on colour constancy

In real scenes, surfaces in different depth planes often differ in the luminance and chromatic content of their illumination. Scene segmentation is therefore an important issue when considering the compensation of illumination changes in our visual perception (lightness and colour constancy). Chromatic adaptation is an important sensory component of colour constancy and has been shown to be linked to the two-dimensional spatial structure of a scene (Werner, 2003 Vision Research 43 1611 - 1623). Here, the question is posed whether this cooperation also extends to the organisation of a scene in depth. The influence of depth on colour constancy was tested by introducing stereo disparity, whereby the test patch and background were perceived in either the same or one of five different depth planes (1.9-57 min of arc). There were no additional cues to depth such as shadows or specular highlights. For consistent illumination changes, colour constancy was reduced when the test patch and background were separated in depth, indicating a reduction of contextual influences. An interaction was found between the influences of stereo depth and spatial frequency on colour constancy. In the case of an inconsistent illumination change, colour constancy was reduced if the test patch and background were in the same depth plane (2-D condition), but not if they were separated in depth (3-D condition). Furthermore, colour constancy was slightly better in the 3-D inconsistent condition than in the 2-D inconsistent condition. It is concluded that depth segmentation supports colour constancy in scenes with inconsistent illumination changes. Processes of depth segmentation are implemented at an early sensory stage of colour constancy, and they define visual regions within which the effects of illuminant changes are discounted for separately. The results support recent models that posit such implementation of scene segmentation in colour constancy.     

Book reviews

Confucian Traditions in East Asian Modernity: moral education and economic culture in Japan and the four mini‐dragons Tu Wei‐Ming (Ed.), 1996 Cambridge, MA, Harvard University Press ii + 418pp., hb £28.50, pb £12.50, ISBN 0 674 16086 X (hb)

The Recluse of Loyang: Shao Yung and the moral evolution of early Sung thought Don J. Wyatt, 1996 Honolulu, University of Hawaii Press xii + 340 pp., hb (price not given), ISBN 0 8248 1755 9

Rude Awakenings: Zen, the Kyoto School and questions of nationalism James W. Heisig & John C. Maraludo (Eds), 1995 Honolulu, University of Hawaii Press hb $40.00, pb $19.95

Untying the Knots in Buddhism. Selected essays Buddhist Tradition Series Volume 28, 1997 Alex Wayman 1997 Delhi, Motilal Banarsidass x + 618 pp, hb Rs. 495; ISBN 81 208 1321 9

Historical Dictionary of Hinduism Historical Dictionaries of Religions, Philosophies, and Movements, No. 13 Bruce M. Sullivan 1997 Lanham, MD & London, The Scarecrow Press xviii, 346 pp, pb £46.55, ISBN 0 8108 3327 1

Dictionary of Philosophy and Religion. Eastern and Western thought (New and enlarged edition; first 1980) William L. Reese, 1996 New York, Humanities Press xiv + 856 pp., pb, ISBN 0 391 03864 8     

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Linear systems analysis of infant visual pattern preferences

Karmel's check-pattern preference data for 13-week-old infants were reanalyzed using linear systems analysis. The two-dimensional Fourier amplitude spectrum was calculated for each of his eight checkerboard and random check patterns. The mean contrast sensitivity data for 3-month-old infants of Banks and Salapatek and the spatial frequency amplitudes of the patterns were used to derive three metrics to predict the looking times observed by Karmel. One was based on the sensitivity of the visual system to the single pattern component highest above threshold (maximum amplitude), the second was based on the total amount of pattern energy above threshold (total summation), and the third was based on the maximum amplitude with summation over nearby spatial frequency components (limited summation). The predictive power of the maximum amplitude and the total summation metrics depended on whether the pattern type was checkerboard or random check. The limited summation metric predicted looking times well for both pattern types. A linear function of the logarithm of the limited summation metric accounted for 91% of the total variance in looking time.