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Depth discrimination of constant angular size stimuli in action space: role of accommodation and convergence cues.

Naceri A, Moscatelli A, Chellali R - Front Hum Neurosci (2015)

Bottom Line: We replicated the task in virtual and real environments and we found that the performance was significantly different between the two environments.Whereas, in virtual reality (VR) the responses were significantly less precise, although, still above chance level in 16 of the 20 observers.The values of Weber fractions estimated in our study were compared to those reported in previous studies in peripersonal and action space.

View Article: PubMed Central - PubMed

Affiliation: Department of Cognitive Neuroscience, Cognitive Interaction Technology Center of Excellence (CITEC), Bielefeld University Bielefeld, Germany.

ABSTRACT
In our daily life experience, the angular size of an object correlates with its distance from the observer, provided that the physical size of the object remains constant. In this work, we investigated depth perception in action space (i.e., beyond the arm reach), while keeping the angular size of the target object constant. This was achieved by increasing the physical size of the target object as its distance to the observer increased. To the best of our knowledge, this is the first time that a similar protocol has been tested in action space, for distances to the observer ranging from 1.4-2.4 m. We replicated the task in virtual and real environments and we found that the performance was significantly different between the two environments. In the real environment, all participants perceived the depth of the target object precisely. Whereas, in virtual reality (VR) the responses were significantly less precise, although, still above chance level in 16 of the 20 observers. The difference in the discriminability of the stimuli was likely due to different contributions of the convergence and the accommodation cues in the two environments. The values of Weber fractions estimated in our study were compared to those reported in previous studies in peripersonal and action space.

No MeSH data available.


GLMM fit and count data (N = 12) in real objects experiment. The response was accurate and precise in all participants.
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Figure 4: GLMM fit and count data (N = 12) in real objects experiment. The response was accurate and precise in all participants.

Mentions: Figure 4 shows the model fit (solid lines) and the observed proportions (circles). The fixed effect accounting for the slope was highly significant (β = 6.82, p < 0.001), indicating a very high precision of the response. The JND was equal to 0.10 ± 0.01 m (JND ± Standard Error; 95% Confidence Interval: 0.08–0.11 m), corresponding to a Weber fraction of 0.05. In this condition, values of β were all significantly greater than 0 indicating that all observers were able to perceive depth, which indicates that participants did not rely on the target apparent size in their depth judgments.


Depth discrimination of constant angular size stimuli in action space: role of accommodation and convergence cues.

Naceri A, Moscatelli A, Chellali R - Front Hum Neurosci (2015)

GLMM fit and count data (N = 12) in real objects experiment. The response was accurate and precise in all participants.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4584972&req=5

Figure 4: GLMM fit and count data (N = 12) in real objects experiment. The response was accurate and precise in all participants.
Mentions: Figure 4 shows the model fit (solid lines) and the observed proportions (circles). The fixed effect accounting for the slope was highly significant (β = 6.82, p < 0.001), indicating a very high precision of the response. The JND was equal to 0.10 ± 0.01 m (JND ± Standard Error; 95% Confidence Interval: 0.08–0.11 m), corresponding to a Weber fraction of 0.05. In this condition, values of β were all significantly greater than 0 indicating that all observers were able to perceive depth, which indicates that participants did not rely on the target apparent size in their depth judgments.

Bottom Line: We replicated the task in virtual and real environments and we found that the performance was significantly different between the two environments.Whereas, in virtual reality (VR) the responses were significantly less precise, although, still above chance level in 16 of the 20 observers.The values of Weber fractions estimated in our study were compared to those reported in previous studies in peripersonal and action space.

View Article: PubMed Central - PubMed

Affiliation: Department of Cognitive Neuroscience, Cognitive Interaction Technology Center of Excellence (CITEC), Bielefeld University Bielefeld, Germany.

ABSTRACT
In our daily life experience, the angular size of an object correlates with its distance from the observer, provided that the physical size of the object remains constant. In this work, we investigated depth perception in action space (i.e., beyond the arm reach), while keeping the angular size of the target object constant. This was achieved by increasing the physical size of the target object as its distance to the observer increased. To the best of our knowledge, this is the first time that a similar protocol has been tested in action space, for distances to the observer ranging from 1.4-2.4 m. We replicated the task in virtual and real environments and we found that the performance was significantly different between the two environments. In the real environment, all participants perceived the depth of the target object precisely. Whereas, in virtual reality (VR) the responses were significantly less precise, although, still above chance level in 16 of the 20 observers. The difference in the discriminability of the stimuli was likely due to different contributions of the convergence and the accommodation cues in the two environments. The values of Weber fractions estimated in our study were compared to those reported in previous studies in peripersonal and action space.

No MeSH data available.