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Understanding the Benefits of Gaze
Enhanced Visual Search
Pernilla Qvarfordt, Jacob T. Biehl, Gene Golovchinsky and Tony Dunnigan
FX Palo Alto LaboratoryPalo Alto, California, USA
Inspecting images is common:
• Radiologist inspect medical images• Airport security inspects x-rays of
luggage• Satellite images are inspect for
threats• Quality control of products often
include visual inspection
Visual search is error prone
• We miss looking everywhere– Radiologist overall error
rate ~20%• (Goddard et al., 2001)
• Current solutions:– Systematic inspection for
all parts of the image– Documentation of review
process– Second reviewer– Pattern recognitions
models (e.g CAD)
(From Mello-Thoms et al. ETRA 2002)
Past research on improving visual
inspection• Training
– Prescribed scan paths• Kollera, Drury and Schwaninger (2009), Nickles, Melloy and
Gramapadhye (2003)
– Scan paths from expert to guide novices • Sadasvian et al. (2005)
• Improving user interfaces– Augementing display of images
• Haiman et al (2004)
– Segmentation of images• Forlines and Balakrishnan (2009)
– Re-presentation of viewed but not selected regions • Nodine and Kundel (1987)
Two phase inspection method
Phase 1 Phase 2
Gaze Data
Detect fixations
Cluster fixations
Determine clusters to exclude
Experimental design• 2 x 2 within-subject design & 8
participants
• 24 images: 6 images per condition– 1 training image per condition
• 260-300 shapes– ~25 x 25 pixels
• 5-20 targets per image (random)– 10-40 close distractors
• 67.5 sec per phase– Each segment shown 7.5 sec
• Gaze block: 270 ms threshold to block cluster
• Tobii X120 Eye tracker & 18” CRT Monitor
Gaze blockNo block
Segm
entationF
ull image
Target Close distractors
Results: Performance
• Overall no difference in True Positive identifications after both phases
• Increase in True Positive rate in 2nd phase (Block + full image)– Near sig. interaction
• Increase in FN not viewed in 1st phase transitioning to TP in 2nd phase (Block + full image)– Sig. interaction
• Significant reduced mental workload (TLX) for Gaze Block
Results: Performance
• Overall no difference in True Positive identifications after both phases
• Increase in True Positive rate in 2nd phase (Block + full image)– Near sig. interaction
• Increase in FN not viewed in 1st phase transitioning to TP in 2nd phase (Block + full image)– Sig. interaction
• Significant reduced mental workload (TLX) for Gaze Block
Results: Gaze Behavior
• Longer durations on True Positives than on False Negatives– Inline with previous research:
• (Nodine and Kundel, 1987; Manning, Ethell and Donovan, 2001)
• Adopt to fixation length– Longer fixation in phase 2
– Sig. shorter fixation on FN viewed in phase 1 with gaze block
550 ms 1032 ms
Future work
• How to use gaze patterns to guide inspectors to better performance?– Optimize use of the two phases
• How to combine information from gaze and image processing to guide inspectors to important parts of the image?
Conclusion
• Two phase inspection method– Reduces workload (with gaze block)– Have positive effect on FN not viewed
transitioning to TP during– Possible to estimate targets benefiting
fromsecond review