Perceptual and cognitive processes in augmented reality – comparison between binocular and monocular presentations

In the present study, we investigated the difference between monocular augmented reality (AR) and binocular AR in terms of perception and cognition by using a task that combines the flanker task with the oddball task. A right- or left-facing arrowhead was presented as a central stimulus at the central vision, and participants were instructed to press a key only when the direction in which the arrowhead faced was a target. In a small number of trials, arrowheads that were facing in the same or opposite direction (flanker stimuli) were presented beside the central stimulus binocularly or monocularly as an AR image. In the binocular condition, the flanker stimuli were presented to both eyes, and, in the monocular condition, only to the dominant eye. The results revealed that participants could respond faster in the binocular condition than in the monocular one; however, only when the flanker stimuli were in the opposite direction was the response faster in the monocular condition. Moreover, the results of event-related brain potentials (ERPs) showed that all stimuli were processed in both the monocular and the binocular conditions in the perceptual stage; however, the influence of the flanker stimuli was attenuated in the monocular condition in the cognitive stage. The influence of flanker stimuli might be more unstable in the monocular condition than in the binocular condition, but more precise examination should be conducted in a future study.

Assessment of objective ocular cyclodeviation under monocular condition and binocular condition using fundus photography

ObjectiveThe relationship between retinal structure and function of glaucomatous eyes has attracted a great deal of research attention. However, visual field tests are conducted under monocular condition, and ophthalmic imaging was performed in patients without occlusion. We aimed to assess the objective ocular cyclodeviation between monocular occlusion and binocular conditions using fundus photography.Methods and analysisThis study included 76 healthy participants. We obtained six photos of the right eye of each patient using fundus photography. Three of the photographs were taken under monocular conditions, and the other three, under binocular conditions. We measured the optic disc margin-fovea angle (MFA) of the line connecting one point of the disc limbus and the fovea. One-way repeated analysis of variance was used to compare the angles under both conditions. We also examined the direction of ocular rotation under the binocular condition regarding the monocular condition.ResultsThe MFAs were 12.12°±3.83° and 12.19°±3.95° under the monocular and binocular conditions, respectively. There was no significant difference in both MFAs (F=1.19, p=0.28). The mean cyclodeviation was 0.07°±0.80° (range: −2.40° to +2.75°). A total of 38 eyes showed excycloduction, while another 38 showed incycloduction.ConclusionSignificant cyclodeviation did not occur regardless of the existence of an occlusion. When examining the relationship between retinal structure and function, the difference in rotation angle under both conditions need not be taken into consideration if the other disease did not cause pathological cyclodeviation.

Six-Month-Old Infants' Perception of the Hollow Face Illusion: Evidence for a General Convexity Bias

Corrow, Granrud, Mathison, and Yonas (2011, Perception, 40, 1376–1383) found evidence that 6-month-old infants perceive the hollow face illusion. In the present study we asked whether 6-month-old infants perceive illusory depth reversal for a nonface object and whether infants' perception of the hollow face illusion is affected by mask orientation inversion. In experiment 1 infants viewed a concave bowl, and their reaches were recorded under monocular and binocular viewing conditions. Infants reached to the bowl as if it were convex significantly more often in the monocular than in the binocular viewing condition. These results suggest that infants perceive illusory depth reversal with a nonface stimulus and that the infant visual system has a bias to perceive objects as convex. Infants in experiment 2 viewed a concave face-like mask in upright and inverted orientations. Infants reached to the display as if it were convex more in the monocular than in the binocular condition; however, mask orientation had no effect on reaching. Previous findings that adults' perception of the hollow face illusion is affected by mask orientation inversion have been interpreted as evidence of stored-knowledge influences on perception. However, we found no evidence of such influences in infants, suggesting that their perception of this illusion may not be affected by stored knowledge, and that perceived depth reversal is not face-specific in infants.

A New Stereotest for Strabismologists: The Covered two Pencil Test

Purpose The two pencil test (TPT) checks the ability to perform a simple visual-motor task. The test is only partially based on intact stereopsis, since monocular depth perception clues are involved. To overcome this shortcoming, a new test variant has been developed and tested. Methods By covering the tip of the examiner's rod, monocular cues should be drastically reduced. Twenty normal subjects performed the TPT and the covered two pencil test (CTPT) under monocular and binocular conditions. Each test condition was repeated 15 times. Four subjects were retested by three different examiners in order to determine the observer variation. Differences between the accuracy and observer variation of the two test variants under monocular and binocular condition were compared using the paired t test. Results The average difference between monocular and binocular accuracy was for the TPT 1.26 cm and for the CTPT 2.37 cm (p<0.0005). The average coefficients of variation of both test variants were similar, for the TPT 0.28 and for the CTPT 0.33 (p>0.1). Conclusions This study demonstrates that covering the tip of the examiner's rod approximately doubles the differences between monocular and binocular accuracy. Therefore, covering seems to reduce monocular cues and increase the stereoscopic value of the TPT.

Interaction between Perspective Visual Cues and Monocular versus Binocular Vision in the Perception of Pitch Subjective Vertical

In a pitch vertical adjustment, a rectangular and plane surface (rod) could be assessed as being upright when its lateral sides looks parallel. According to this hypothesis, geometrical analysis underscores that adjustment errors relative to the vertical are a function of the width of the rod, its gradient of perspective, and its distance from the observer's eyes. In order to verify this relationship, thirty-two subjects assessed pitch subjective vertical (PSV) in two visual conditions (monocular versus binocular) by rotating in darkness different luminous rods in the median plane. The trapezoid rods varied both in their width and in their angles of convergence measured from each lateral side. The rod-to-eyes distance was fixed at 60 cm and the length of the rod was 25 cm. The results showed that the data fitted in with the geometrical analysis in monocular and binocular conditions. However, in the binocular condition the weight of the shape visual cues decreased considerably. Moreover, a significant constant error remained even with the rectangular surface. It is concluded that rod adjustment to PSV is essentially a visual process similar to the perception of surface slant as Perrone's model develops it (1982 Perception11 641 – 654). Indeed, the visual cues involved in the vertical adjustment task are in accordance with this model. Also, the constant error observed in PSV could be explained by the deviation of the subjective eye level which Perrone supposes to account for the slant underestimation in his model.