Attention deployment in natural scenes: Higher-order scene statistics rather than semantics modulate the N2pc component.

Which properties of a natural scene affect visual search? We consider the alternative hypotheses that low-level statistics, higher-level statistics, semantics, or layout affect search difficulty in natural scenes. Across three experiments (n = 20 each), we used four different backgrounds that preserve distinct scene properties: (a) natural scenes (all experiments); (b) 1/f noise (pink noise, which preserves only low-level statistics and was used in Experiments 1 and 2); (c) textures that preserve low-level and higher-level statistics but not semantics or layout (Experiments 2 and 3); and (d) inverted (upside-down) scenes that preserve statistics and semantics but not layout (Experiment 2). We included "split scenes" that contained different backgrounds left and right of the midline (Experiment 1, natural/noise; Experiment 3, natural/texture).

Bimodal moment-by-moment coupling in perceptual multistability.

Multistable perception occurs in all sensory modalities, and there is ongoing theoretical debate about whether there are overarching mechanisms driving multistability across modalities. Here we study whether multistable percepts are coupled across vision and audition on a moment-by-moment basis. To assess perception simultaneously for both modalities without provoking a dual-task situation, we query auditory perception by direct report, while measuring visual perception indirectly via eye movements.

High visual salience of alert signals can lead to a counterintuitive increase of reaction times.

It is often assumed that rendering an alert signal more salient yields faster responses to this alert. Yet, there might be a trade-off between attracting attention and distracting from task execution. Here we tested this in four behavioral experiments with eye-tracking using an abstract alert-signal paradigm.

Attentional cueing: Gaze is harder to override than arrows.

Gaze is an important and potent social cue to direct others' attention towards specific locations. However, in many situations, directional symbols, like arrows, fulfill a similar purpose. Motivated by the overarching question how artificial systems can effectively communicate directional information, we conducted two cueing experiments.

Multisensory cues for walking in virtual reality: humans combine conflicting visual and self-motion information to reproduce distances.

When humans walk, it is important for them to have some measure of the distance they have traveled. Typically, many cues from different modalities are available, as humans perceive both the environment around them (for example, through vision and haptics) and their own walking. Here, we investigate the contribution of visual cues and nonvisual self-motion cues to distance reproduction when walking on a treadmill through a virtual environment by separately manipulating the speed of a treadmill belt and of the virtual environment.

Effects of interpreting a dynamic geometric cue as gaze on attention allocation.

Gaze is a powerful cue for directing attention. We investigate the interpretation of an abstract figure as gaze modulates its efficacy as an attentional cue. In each trial, two vertical lines on a central disk moved to one side (left or right).

Exploration behavior after reversals is predicted by STN-GPe synaptic plasticity in a basal ganglia model.

Humans can quickly adapt their behavior to changes in the environment. Classical reversal learning tasks mainly measure how well participants can disengage from a previously successful behavior but not how alternative responses are explored. Here, we propose a novel 5-choice reversal learning task with alternating position-reward contingencies to study exploration behavior after a reversal.

Evaluating the Effects of Virtual Reality Environment Learning on Subsequent Robot Teleoperation in an Unfamiliar Building.

Using a map in an unfamiliar environment requires identifying correspondences between elements of the map's allocentric representation and elements in egocentric views. Aligning the map with the environment can be challenging. Virtual reality (VR) allows learning about unfamiliar environments in a sequence of egocentric views that correspond closely to the perspectives and views that are experienced in the actual environment.

Attention does not spread automatically along objects: Evidence from the pupillary light response.

Objects influence attention allocation; when a location within an object is cued, participants react faster to targets appearing in a different location within this object than on a different object. Despite consistent demonstrations of this object-based effect, there is no agreement regarding its underlying mechanisms. To test the most common hypothesis that attention spreads automatically along the cued object, we utilized a continuous, response-free measurement of attentional allocation that relies on the modulation of the pupillary light response.

Slipping while counting: gaze-gait interactions during perturbed walking under dual-task conditions.

Walking is a complex task. To prevent falls and injuries, gait needs to constantly adjust to the environment. This requires information from various sensory systems; in turn, moving through the environment continuously changes available sensory information.

Low-high-low or high-low-high? Pattern effects on sequential auditory scene analysis.

Sequential auditory scene analysis (ASA) is often studied using sequences of two alternating tones, such as ABAB or ABA_, with "_" denoting a silent gap, and "A" and "B" sine tones differing in frequency (nominally low and high). Many studies implicitly assume that the specific arrangement (ABAB vs ABA_, as well as low-high-low vs high-low-high within ABA_) plays a negligible role, such that decisions about the tone pattern can be governed by other considerations. To explicitly test this assumption, a systematic comparison of different tone patterns for two-tone sequences was performed in three different experiments.

Action-based predictions affect visual perception, neural processing, and pupil size, regardless of temporal predictability.

Sensory consequences of one's own action are often perceived as less intense, and lead to reduced neural responses, compared to externally generated stimuli. Presumably, such sensory attenuation is due to predictive mechanisms based on the motor command (efference copy). However, sensory attenuation has also been observed outside the context of voluntary action, namely when stimuli are temporally predictable.

Pupillometry as an integrated readout of distinct attentional networks.

The course of pupillary constriction and dilation provides an easy-to-access, inexpensive, and noninvasive readout of brain activity. We propose a new taxonomy of factors affecting the pupil and link these to associated neural underpinnings in an ascending hierarchy. In addition to two well-established low-level factors (light level and focal distance), we suggest two further intermediate-level factors, alerting and orienting, and a higher-level factor, executive functioning.

Icy road ahead-rapid adjustments of gaze-gait interactions during perturbed naturalistic walking.

Most humans can walk effortlessly across uniform terrain even when they do not pay much attention to it. However, most natural terrain is far from uniform, and we need visual information to maintain stable gait. Recent advances in mobile eye-tracking technology have made it possible to study, in natural environments, how terrain affects gaze and thus the sampling of visual information.

Gaze During Locomotion in Virtual Reality and the Real World.

How vision guides gaze in realistic settings has been researched for decades. Human gaze behavior is typically measured in laboratory settings that are well controlled but feature-reduced and movement-constrained, in sharp contrast to real-life gaze control that combines eye, head, and body movements. Previous real-world research has shown environmental factors such as terrain difficulty to affect gaze; however, real-world settings are difficult to control or replicate.

Pupillometry in auditory multistability.

In multistability, a constant stimulus induces alternating perceptual interpretations. For many forms of visual multistability, the transition from one interpretation to another ("perceptual switch") is accompanied by a dilation of the pupil. Here we ask whether the same holds for auditory multistability, specifically auditory streaming.

Perceptual Difficulty Persistently Increases Dominance in Binocular Rivalry-Even Without a Task.

A major objective of perception is the reduction of uncertainty about the outside world. Eye-movement research has demonstrated that attention and oculomotor control can subserve the function of decreasing uncertainty in vision. Here, we ask whether a similar effect exists for awareness in binocular rivalry, when two distinct stimuli presented to the two eyes compete for awareness.

Parameter dependence in visual pattern-component rivalry at onset and during prolonged viewing.

In multistability, perceptual interpretations ("percepts") of ambiguous stimuli alternate over time. There is considerable debate as to whether similar regularities govern the first percept after stimulus onset and percepts during prolonged presentation. We address this question in a visual pattern-component rivalry paradigm by presenting two overlaid drifting gratings, which participants perceived as individual gratings passing in front of each other ("segregated") or as a plaid ("integrated").

Salience-based object prioritization during active viewing of naturalistic scenes in young and older adults.

Whether fixation selection in real-world scenes is guided by image salience or by objects has been a matter of scientific debate. To contrast the two views, we compared effects of location-based and object-based visual salience in young and older (65 + years) adults. Generalized linear mixed models were used to assess the unique contribution of salience to fixation selection in scenes.

Fixation durations in natural scene viewing are guided by peripheral scene content.

Fixation durations provide insights into processing demands. We investigated factors controlling fixation durations during scene viewing in two experiments. In Experiment 1, we tested the degree to which fixation durations adapt to global scene processing difficulty by manipulating the contrast (from original contrast to isoluminant) and saturation (original vs.

Picture-evoked changes in pupil size predict learning success in children.

Episodic memory, the ability to remember past events in time and place, develops during childhood. Much knowledge about the underlying neuronal mechanisms has been gained from methods not suitable for children. We applied pupillometry to study memory encoding and recognition mechanisms.

Anterior insula reflects surprise in value-based decision-making and perception.

The brain has been theorized to employ inferential processes to overcome the problem of uncertainty. Inference is thought to underlie neural processes, including in disparate domains such as value-based decision-making and perception. Value-based decision-making commonly involves deliberation, a time-consuming process that requires conscious consideration of decision variables.

Cognition modulates action-to-perception transfer in ambiguous perception.

Can cognition penetrate action-to-perception transfer? Participants observed a structure-from-motion cylinder of ambiguous rotation direction. Beforehand, they experienced one of two mechanical models: An unambiguous cylinder was connected to a rod by either a belt (cylinder and rod rotating in the same direction) or by gears (both rotating in opposite directions). During ambiguous cylinder presentation, mechanics and rod were invisible, making both conditions visually identical.

Continuous flash suppression: Manual action affects eye movements but not the reported percept.

Diverse paradigms, including ambiguous stimuli and mental imagery, have suggested a shared representation between motor and perceptual domains. We examined the effects of manual action on ambiguous perception in a continuous flash suppression (CFS) experiment. Specifically, we asked participants to try to perceive a suppressed grating while rotating a manipulandum.