Keynote Speakers

Martin Banks

University of California, Berekely, United States

Humans exhibit machine-like eye movements in space and time while performing demanding acuity tasks. To these, we used an adaptive-optics imaging and display system to present ultra-sharp Vernier acuity stimuli briefly every two seconds while simultaneously measuring eye movements, including precisely where on the retina each stimulus fell. We found that drifts and microsaccades combined to confine the landing location of the anticipated stimulus to a tiny retinal region centered on the preferred retinal locus (PRL). The variance of landing location was smallest at the time of stimulus presentation and a few hundred milliseconds after. We correlated where the stimulus fell in space and time with correct or incorrect responses. The PRL and a small area around it, including the anatomical fovea, conferred the best acuity. Acuity declined consistently in the rare events in which the stimulus fell more than 7–10minarc from the PRL. We also found that acuity was best when the last microsaccade occurred sufficiently prior to stimulus presentation. Our findings reveal a highly evolved oculomotor system where gaze direction during fixation is rarely far enough from the PRL to compromise visual resolution when a person makes natural fixational eye movements.

Anne Böckler-Raettig

Julius-Maximilians-Universität Würzburg, Germany

Gaze direction is an important social signal that structures conversations and supports joint actions. Recent studies, including our own, have pointed towards the role of context in gaze processing and behavior, showing, for instance, that basic attention capture by direct gaze is systematically modulated by the emotional expression of the face. Similarly, the effects of eye contact on person evaluation and subsequent cooperation in more naturalistic conversation settings depended on the emotional dynamics of the interaction. Contrasting with these findings of context-sensitivity, however, (our) other studies suggest stability: When listening to narrations of autobiographical experiences, participants’ empathy and perspective taking were largely independent of narrators’ gaze behavior (and even visibility of their eyes). Relatedly, during real-life dyadic conversations, spontaneous gaze behavior (tracked with mobile glasses), seemed surprisingly stable to emotional context factors (e.g., the topic of the conversation). In an attempt to reconcile these seemingly contradictory patterns, I will propose a (preliminary) categorization of factors and demands that influence whether and how context-information is integrated or ignored when interpreting and using gaze cues.

Ignace Hooge

Utrecht University, The Netherlands

Johanna Kaakinen

University of Turku, Finland

Christoph Völter

Max-Planck-Institute for Evolutionary Anthropology, Leipzig, Germany

Eye tracking provides a non-invasive method for investigating cognition across species by revealing how animals allocate attention and respond to events that potentially violate their expectations. This talk synthesizes recent eye-tracking research with pet dogs and great apes to explore how these species process physical events, cues of agency, and communicative signals. With dogs, we investigated how ostensive human communication modulates object encoding in a violation-of-expectation paradigm. Similar to human infants, dogs selectively showed enhanced memory for object identity, but not location, following direct eye contact. Mobile eye tracking during real-world interactions reveals that the combination of pointing and head turns most effectively directs dogs’ visual attention to a referent, exceeding the influence of non-communicative directional cues. Further studies indicate that dogs form implicit expectations about occlusion and launching events, show limited sensitivity to gravity-related violations, and orient toward motion cues associated with animacy, such as self-propelled movement and variable speed. Ongoing eye-tracking studies with great apes investigate agency attribution and action understanding. Using modified Frith–Happé animations and goal-based action-prediction paradigms, we examine whether adult humans and nonhuman apes differentiate between non-interactive motion, goal-directed and mentalistic interactions, and whether agency cues enable intention attribution to unfamiliar agents. Together, this work highlights the potential of eye tracking to uncover shared and species-specific cognitive mechanisms across dogs, nonhuman apes, and humans.