Evaluating the influence of a fixated object's spatio-temporal properties on gaze control

The functional arrangement of objects biases gaze direction

A growing number of studies suggest that semantic knowledge can influence the control of gaze in scenes. For example, observers are more likely to look toward objects that are semantically related to the currently fixated object. Recent evidence also suggests that an object's functional orientation can bias gaze direction. However, it is unknown whether these semantic and functional relationships can interact to determine gaze control. To address this issue, the present study assessed whether the functional arrangement of multiple objects can influence gaze control. Participants fixated a central object (e.g., a key) flanked by two peripheral objects. After a brief delay, participants were free to shift their gaze toward the peripheral object of their choice. One of the peripheral objects was semantically related to the central object (e.g., a lock), and the objects were arranged to depict a functional or non-functional interaction (e.g., a key pointing toward or away from a lock). When the orientation of the central object was manipulated, participants were more likely to look in the direction this object was pointing. Moreover, the functional arrangement of objects modulated this central orienting bias. However, when the orientation of the peripheral objects was manipulated, only the peripheral objects' semantic relationships influenced gaze control. Together, these findings suggest that functional relationships play an important role in the allocation of gaze, and can interact with semantic relationships to determine gaze control.

Feature integration is unaffected by saccade landing point, even when saccades land outside of the range of regular oculomotor variance

The experience of our visual surroundings appears continuous, contradicting the erratic nature of visual processing due to saccades. A possible way the visual system can construct a continuous experience is by integrating presaccadic and postsaccadic visual input. However, saccades rarely land exactly at the intended location. Feature integration would therefore need to be robust against variations in saccade execution to facilitate visual continuity. In the current study, observers reported a feature (color) of the saccade target, which occasionally changed slightly during the saccade. In transsaccadic change-trials, observers reported a mixture of the pre- and postsaccadic color, indicating transsaccadic feature integration. Saccade landing distance was not a significant predictor of the reported color. Next, to investigate the influence of more extreme deviations of saccade landing point on color reports, we used a global effect paradigm in a second experiment. In global effect trials, a distractor appeared together with the saccade target, causing most saccades to land in between the saccade target and the distractor. Strikingly, even when saccades land further away (up to 4°) from the saccade target than one would expect under single target conditions, there was no effect of saccade landing point on the reported color. We reason that saccade landing point does not affect feature integration, due to dissociation between the intended saccade target and the actual saccade landing point. Transsaccadic feature integration seems to be a mechanism that is dependent on visual spatial attention, and, as a result, is robust against variance in saccade landing point.