Impairment of cyclopean surface processing by disparity-defined masking stimuli.

Binocular disparity signals allow for the estimation of three-dimensional shape, even in the absence of monocular depth cues. The perception of such disparity-defined form depends, however, on the linkage of multiple disparity measurements over space. Performance limitations in cyclopean tasks thus inform us about errors arising in disparity measurement and difficulties in the linkage of such measurements. We used a cyclopean orientation discrimination task to examine the perception of disparity-defined form. Participants were presented with random-dot sinusoidal modulations in depth and asked to report whether they were clockwise or counter-clockwise rotated. To assess the effect of different noise structures on measurement and linkage processes, task performance was measured in the presence of binocular, random-dot masks, structured as either antiphase depth sinusoids, or as random distributions of dots in depth. For a fixed number of surface dots, the ratio of mask-to-surface dots was varied to obtain thresholds for orientation discrimination. Antiphase masks were found to be more effective than random depth masks, requiring a lower mask-to-surface dot ratio to inhibit performance. For antiphase masks, performance improved with decreased cyclopean frequency, increased disparity amplitude, and/or an increase in the total number of stimulus dots. Although a cross-correlation model of disparity measurement could account for antiphase mask performance, random depth masking effects were consistent with limitations in relative disparity processing. This suggests that performance is noise-limited for antiphase masks and complexity-limited for random masks. We propose that use of differing mask types may prove effective in understanding these distinct forms of impairment.

A bedside application-based assessment of spatial orientation and memory: approaches and lessons learned.

Spatial orientation and memory deficits are an often overlooked and potentially powerful early marker for pathological cognitive decline. Pen-and-paper tests for spatial abilities often do not coincide with actual navigational performance due to differences in spatial perspective and scale. Mobile devices are becoming increasingly useful in a clinical setting, for patient monitoring, clinical decision-making, and information management. The same devices have positional information that may be useful for a scale appropriate point-of-care test for spatial ability. We created a test for spatial orientation and memory based on pointing within a single room using the sensors in mobile phone. The test consisted of a baseline pointing condition to which all other conditions were compared, a spatial memory condition with eyes-closed, and two body rotation conditions (real or mental) where spatial updating were assessed. We examined the effectiveness of the sensors from a mobile phone for measuring pointing errors in these conditions in a sample of healthy young individuals. We found that the sensors reliably produced appropriate azimuth and elevation pointing angles for all of the 15 targets presented across multiple participants and days. Within-subject variability was below 6° elevation and 10° azimuth for the control condition. The pointing error and variability increased with task difficulty and correlated with self-report tests of spatial ability. The lessons learned from the first tests are discussed as well as the outlook of this application as a scientific and clinical bedside device. Finally, the next version of the application is introduced as an open source application for further development.

Texting while walking: An expensive switch cost.

Texting while walking has been highlighted as a dangerous behavior that leads to impaired judgment and accidents. This impairment could be due to task switching which involves activation of the present task and the inhibition of the previous task. However, the relative contributions of these processes and their brain activity have not yet been studied. We addressed this gap by asking participants to discriminate the orientation of an oncoming human shape in a virtual environment while they were: i) walking on a treadmill, or ii) texting while walking on a treadmill. Participants' performance (i.e., correctly identifying if a walker would pass them to their left or right) and electroencephalography (EEG) data was collected. Unsurprisingly, we found that participants performed better while they were only walking than when texting while walking. However, we also found that the diminished performance is differently related to task set inhibition and task set activation in the two conditions. The alpha oscillations, which can be used as an index of task inhibition, have a significantly different relation to performance in the two conditions, the relation being negative when subjects are texting. This may indicate that the more inhibition is needed, the more the performance is affected by texting. To our knowledge, this is the first study to investigate the brain signature of task switching in texting while walking. This finding is the first step in identifying the source of impaired judgment in texting pedestrians and in finding viable solutions to reduce the risks.

Visual attention and action: How cueing, direct mapping, and social interactions drive orienting.

Despite considerable interest in both action perception and social attention over the last 2 decades, there has been surprisingly little investigation concerning how the manual actions of other humans orient visual attention. The present review draws together studies that have measured the orienting of attention, following observation of another's goal-directed action. Our review proposes that, in line with the literature on eye gaze, action is a particularly strong orienting cue for the visual system. However, we additionally suggest that action may orient visual attention using mechanisms, which gaze direction does not (i.e., neural direct mapping and corepresentation). Finally, we review the implications of these gaze-independent mechanisms for the study of attention to action. We suggest that our understanding of attention to action may benefit from being studied in the context of joint action paradigms, where the role of higher level action goals and social factors can be investigated.

Attentional accounting: Voluntary spatial attention increases budget category prioritization.

Too often, people fail to prioritize the most important activities, life domains, and budget categories. One reason for misplaced priorities, we argue, is that activities and categories people have frequently or recently attended to seem higher priority than other activities and categories. In Experiment 1, participants were cued to direct voluntary spatial attention toward 1 side of a screen while images depicting different budget categories were presented: 1 category on the cued side and 1 on the noncued side of the screen. Participants rated cued budget categories as higher priority than noncued budget categories. Cued attention also increased perceived distinctiveness, and a mediation model was consistent with the hypothesis that distinctiveness mediates the effect of cued attention on prioritization. Experiment 2 orthogonally manipulated 2 components of a spatial cuing manipulation-heightened visual attention and heightened mental attention-to examine how each influences prioritization. Visual attention and mental attention additively increased prioritization. In Experiment 3, attention increased prioritization even when prioritization decisions were incentivized, and even when heightened attention was isolated from primacy and recency. Across experiments, cued categories were prioritized more than noncued categories even though measures were taken to disguise the purpose of the experiments and manipulate attention incidentally (i.e., as a by-product of an unrelated task). (PsycINFO Database Record

Attentional interference is modulated by salience not sentience.

Spatial cueing of attention occurs when attention is oriented by the onset of a stimulus or by other information that creates a bias towards a particular location. The presence of a cue that orients attention can also interfere with participants' reporting of what they see. It has been suggested that this type of interference is stronger in the presence of socially-relevant cues, such as human faces or avatars, and is therefore indicative of a specialised role for perspective calculation within the social domain. However, there is also evidence that the effect is a domain-general form of processing that is elicited equally with non-social directional cues. The current paper comprises four experiments that systematically manipulated the social factors believed necessary to elicit the effect. The results show that interference persists when all social components are removed, and that visual processes are sufficient to explain this type of interference, thus supporting a domain-general perceptual interpretation of interference.