4,596 research outputs found
Task-demands can immediately reverse the effects of sensory-driven saliency in complex visual stimuli
In natural vision both stimulus features and task-demands affect an observer's attention. However, the relationship between sensory-driven (“bottom-up”) and task-dependent (“top-down”) factors remains controversial: Can task-demands counteract strong sensory signals fully, quickly, and irrespective of bottom-up features? To measure attention under naturalistic conditions, we recorded eye-movements in human observers, while they viewed photographs of outdoor scenes. In the first experiment, smooth modulations of contrast biased the stimuli's sensory-driven saliency towards one side. In free-viewing, observers' eye-positions were immediately biased toward the high-contrast, i.e., high-saliency, side. However, this sensory-driven bias disappeared entirely when observers searched for a bull's-eye target embedded with equal probability to either side of the stimulus. When the target always occurred in the low-contrast side, observers' eye-positions were immediately biased towards this low-saliency side, i.e., the sensory-driven bias reversed. Hence, task-demands do not only override sensory-driven saliency but also actively countermand it. In a second experiment, a 5-Hz flicker replaced the contrast gradient. Whereas the bias was less persistent in free viewing, the overriding and reversal took longer to deploy. Hence, insufficient sensory-driven saliency cannot account for the bias reversal. In a third experiment, subjects searched for a spot of locally increased contrast (“oddity”) instead of the bull's-eye (“template”). In contrast to the other conditions, a slight sensory-driven free-viewing bias prevails in this condition. In a fourth experiment, we demonstrate that at known locations template targets are detected faster than oddity targets, suggesting that the former induce a stronger top-down drive when used as search targets. Taken together, task-demands can override sensory-driven saliency in complex visual stimuli almost immediately, and the extent of overriding depends on the search target and the overridden feature, but not on the latter's free-viewing saliency
Personalization of Saliency Estimation
Most existing saliency models use low-level features or task descriptions
when generating attention predictions. However, the link between observer
characteristics and gaze patterns is rarely investigated. We present a novel
saliency prediction technique which takes viewers' identities and personal
traits into consideration when modeling human attention. Instead of only
computing image salience for average observers, we consider the interpersonal
variation in the viewing behaviors of observers with different personal traits
and backgrounds. We present an enriched derivative of the GAN network, which is
able to generate personalized saliency predictions when fed with image stimuli
and specific information about the observer. Our model contains a generator
which generates grayscale saliency heat maps based on the image and an observer
label. The generator is paired with an adversarial discriminator which learns
to distinguish generated salience from ground truth salience. The discriminator
also has the observer label as an input, which contributes to the
personalization ability of our approach. We evaluate the performance of our
personalized salience model by comparison with a benchmark model along with
other un-personalized predictions, and illustrate improvements in prediction
accuracy for all tested observer groups
Objects predict fixations better than early saliency
Humans move their eyes while looking at scenes and pictures. Eye movements correlate with shifts in attention and are thought to be a consequence of optimal resource allocation for high-level tasks such as visual recognition. Models of attention, such as “saliency maps,” are often built on the assumption that “early” features (color, contrast, orientation, motion, and so forth) drive attention directly. We explore an alternative hypothesis: Observers attend to “interesting” objects. To test this hypothesis, we measure the eye position of human observers while they inspect photographs of common natural
scenes. Our observers perform different tasks: artistic evaluation, analysis of content, and search. Immediately after each presentation, our observers are asked to name objects they saw. Weighted with recall frequency, these objects predict fixations in individual images better than early saliency, irrespective of task. Also, saliency combined with object positions predicts which objects are frequently named. This suggests that early saliency has only an indirect effect on attention, acting
through recognized objects. Consequently, rather than treating attention as mere preprocessing step for object recognition, models of both need to be integrated
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