Classbeacons: Enhancing reflection-inaction of teachers through spatially distributed ambient information

© 2019 Copyright is held by the author/owner(s). ACM Reflection-in-action (RiA) refers to teachers' reflections on their teaching performance during busy classroom routines. RiA is a demanding competence for teachers, but little has been known about how HCI systems could support teachers' RiA during their busy and intensive teaching. To bridge this gap, we design and evaluate an ambient information system named ClassBeacons. ClassBeacons aims to help teachers intuitively reflect-in-action on how to divide time and attention over pupils throughout a lesson. ClassBeacons subtly depicts teachers' division of time and attention over pupils through multiple light-objects distributed over students' desks. Each light-object indicates how long the teacher has been cumulatively around it (helping an adjacent student) by shifting color. A field evaluation with eleven teachers proved that ClassBeacons enhanced teachers' RiA by supporting their sensemaking of ongoing performance and modification of upcoming actions. Furthermore, ClassBeacons was experienced to unobtrusively fit into teachers' routines without overburdening teaching in progress

The Spatial Origin of a Perceptual Transition in Binocular Rivalry

When the left and the right eye are simultaneously presented with incompatible images at overlapping retinal locations, an observer typically reports perceiving only one of the two images at a time. This phenomenon is called binocular rivalry. Perception during binocular rivalry is not stable; one of the images is perceptually dominant for a certain duration (typically in the order of a few seconds) after which perception switches towards the other image. This alternation between perceptual dominance and suppression will continue for as long the images are presented. A characteristic of binocular rivalry is that a perceptual transition from one image to the other generally occurs in a gradual manner: the image that was temporarily suppressed will regain perceptual dominance at isolated locations within the perceived image, after which its visibility spreads throughout the whole image. These gradual transitions from perceptual suppression to perceptual dominance have been labeled as traveling waves of perceptual dominance. In this study we investigate whether stimulus parameters affect the location at which a traveling wave starts. We varied the contrast, spatial frequency or motion speed in one of the rivaling images, while keeping the same parameter constant in the other image. We used a flash-suppression paradigm to force one of the rival images into perceptual suppression. Observers waited until the suppressed image became perceptually dominant again, and indicated the position at which this breakthrough from suppression occurred. Our results show that the starting point of a traveling wave during binocular rivalry is highly dependent on local stimulus parameters. More specifically, a traveling wave most likely started at the location where the contrast of the suppressed image was higher than that of the dominant one, the spatial frequency of the suppressed image was lower than that of the dominant one, and the motion speed of the suppressed image was higher than that of the dominant one. We suggest that a breakthrough from suppression to dominance occurs at the location where salience (the degree to which a stimulus element stands out relative to neighboring elements) of the suppressed image is higher than that of the dominant one. Our results further show that stimulus parameters affecting the temporal dynamics during continuous viewing of rival images described in other studies, also affect the spatial origin of traveling waves during binocular rivalry

Willpower and Conscious Percept: Volitional Switching in Binocular Rivalry

When dissimilar images are presented to the left and right eyes, awareness switches spontaneously between the two images, such that one of the images is suppressed from awareness while the other is perceptually dominant. For over 170 years, it has been accepted that even though the periods of dominance are subject to attentional processes, we have no inherent control over perceptual switching. Here, we revisit this issue in response to evidence that top-down attention can target perceptually suppressed ‘vision for action’ representations in the dorsal stream. We investigated volitional control over rivalry between apparent motion (AM), drifting (DM) and stationary (ST) grating pairs. Observers demonstrated a remarkable ability to generate intentional switches in the AM and D conditions, but not in the ST condition. Corresponding switches in the pursuit direction of optokinetic nystagmus verified this finding objectively. We showed it is unlikely that intentional perceptual switches were triggered by saccadic eye movements, because their frequency was reduced substantially in the volitional condition and did not change around the time of perceptual switches. Hence, we propose that synergy between dorsal and ventral stream representations provides the missing link in establishing volitional control over rivalrous conscious percepts

Levelt’s laws do not predict perception when luminance- and contrast-modulated stimuli compete during binocular rivalry

Incompatible patterns viewed by each of the two eyes can provoke binocular rivalry, a competition of perception. Levelt’s first law predicts that a highly visible stimulus will predominate over a less visible stimulus during binocular rivalry. In a behavioural study, we made a counterintuitive observation: low visibility patterns can predominate over high visibility patterns. Our results show that none of Levelt’s binocular rivalry laws hold when luminance-modulated (LM) patterns compete with contrast-modulated (CM) patterns. We discuss visual saliency, asymmetric feedback, and a combination of both as potential mechanisms to explain the CM versus LM findings. Competing orthogonal LM stimuli do follow Levelt’s laws, whereas only the first two laws hold for competing CM stimuli. The current results provide strong psychophysical evidence for the existence of separate processing stages for LM and CM stimuli

Unobtrusively enhancing reflection-in-action of teachers through spatially distributed ambient information

© 2019 Association for Computing Machinery. Reflecting on their performance during classroom-teaching is an important competence for teachers. Such reflection-inaction (RiA) enables them to optimize teaching on the spot. But RiA is also challenging, demanding extra thinking in teachers’ already intensive routines. Little is known on how HCI systems can facilitate teachers’ RiA during classroom-teaching. To fill in this gap, we evaluate ClassBeacons, a system that uses spatially distributed lamps to depict teachers’ ongoing performance on how they have divided their time and attention over students in the classroom. Empirical qualitative data from eleven teachers in 22 class periods show that this ambient information facilitated teachers’ RiA without burdening teaching in progress. Based on our theoretical grounding and field evaluation, we contribute empirical knowledge about how an HCI system enhanced teachers’ process of RiA as well as a set of design principles for unobtrusively supporting RiA

Predicting visual consciousness electrophysiologically from intermittent binocular rivalry

Purpose: We sought brain activity that predicts visual consciousness. Methods: We used electroencephalography (EEG) to measure brain activity to a 1000-ms display of sine-wave gratings, oriented vertically in one eye and horizontally in the other. This display yields binocular rivalry: irregular alternations in visual consciousness between the images viewed by the eyes. We replaced both gratings with 200 ms of darkness, the gap, before showing a second display of the same rival gratings for another 1000 ms. We followed this by a 1000-ms mask then a 2000- ms inter-trial interval (ITI). Eleven participants pressed keys after the second display in numerous trials to say whether the orientation of the visible grating changed from before to after the gap or not. Each participant also responded to numerous non-rivalry trials in which the gratings had identical orientations for the two eyes and for which the orientation of both either changed physically after the gap or did not. Results: We found that greater activity from lateral occipital-parietal-temporal areas about 180 ms after initial onset of rival stimuli predicted a change in visual consciousness more than 1000 ms later, on re-presentation of the rival stimuli. We also found that less activity from parietal, central, and frontal electrodes about 400 ms after initial onset of rival stimuli predicted a change in visual consciousness about 800 ms later, on re-presentation of the rival stimuli. There was no such predictive activity when the change in visual consciousness occurred because the stimuli changed physically. Conclusion: We found early EEG activity that predicted later visual consciousness. Predictive activity 180 ms after onset of the first display may reflect adaption of the neurons mediating visual consciousness in our displays. Predictive activity 400 ms after onset of the first display may reflect a less-reliable brain state mediating visual consciousness

Negligible fronto-parietal BOLD activity accompanying unreportable switches in bistable perception

The human brain's executive systems have a vital role in deciding and selecting among actions. Selection among alternatives also occurs in the perceptual domain; for instance, when perception switches between interpretations during perceptual bistability. Whether executive systems also underlie this functionality remains debated, with known fronto-parietal concomitants of perceptual switches being variously interpreted as reflecting the switches' cause or as reflecting their consequences. We developed a procedure in which the two eyes receive different inputs and perception demonstrably switches between these inputs, yet the switches themselves are so inconspicuous as to become unreportable, minimizing their executive consequences. Fronto-parietal fMRI BOLD responses that accompanied perceptual switches were similarly minimized in this procedure, indicating that these reflect the switches' consequences rather than their cause. We conclude that perceptual switches do not always rely on executive brain areas and that processes responsible for selection among alternatives may operate outside the brain's executive systems