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Learning and Modulating Spatial Probabilities in Virtual Environments
Chapter 35
Learning and Modulating Spatial Probabilities in Virtual Environments Amy L. Holloway1, Peter Chapman1, Alastair D. Smith2 1University
of Nottingham, Nottingham, United Kingdom; 2University of Plymouth, Plymouth, United Kingdom
BACKGROUND Visual search behavior, in simple two-dimensional arrays, is sensitive to the spatial statistics of target distributions. When the target appears with greater likelihood in one-half of the array, participants become faster at locating it, in comparison to when targets are located on the other (low-probability) side. This phenomenon is known as probability cueing, and appears to operate below a level of conscious awareness (i.e., participants do not report awareness of the distribution when probed after the task). In contrast, studies that have employed large-scale search paradigms, in which full-body movements are required to inspect locations, report that probability cueing is more complex, requiring a combination of stable spatial cues and, when successful, appears to be explicit in nature.
AIMS This research aimed to investigate whether probability cueing could be observed in a virtual environment—a threedimensional medium between visual and large-scale search. The immersive qualities of the environment were manipulated by changing the display size and visual aspects across two experiments. In the final experiment, we investigated whether spatial cueing could be modulated by applying transcranial direct-current stimulation (tDCS) to the right posterior parietal cortex.
METHODS Participants were required to search for a hidden target within a virtual arena, which was displayed on a computer monitor (Study 1) or within an environment simulator (Study 2). In Study 1, the environment consisted of textured walls and flooring. In Study 2, texture was replaced by solid colors (to reduce levels of simulator sickness in the more immersive environment). Participants were not informed that the target was more likely to be located on one side of the array than the other. In Study 3, participants firstly completed a set of baseline trials, followed by 15 min of 1 mA tDCS (anodal, cathodal, or sham) to the right parietal cortex, then two blocks of probability cueing trials on a computer monitor (the same as Study 1). In all experiments, participants were probed for awareness of the manipulation after testing.
RESULTS AND CONCLUSIONS Study 1 Significant cueing effects were demonstrated, as exemplified by reduced search times to targets on the cued side of space. However, participants not express any conscious awareness of the probability cue. This is in line with the visual search literature, suggesting that physical effort may be necessary for explicit learning of the probability cue.
Study 2 No significant cueing effects were found. The removal of textures in the environment may have decreased optic flow, making it difficult for participants to accurately update their spatial location, and represent target statistics, as they explored the Neuroergonomics. http://dx.doi.org/10.1016/B978-0-12-811926-6.00035-X Copyright © 2019 Elsevier Inc. All rights reserved.
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202 SECTION | VI Entries From the Inaugural International Neuroergonomics Conference
environment. Future experiments in immersive environments should, therefore, systematically explore whether probability cueing is related to the level of contextual information present in the environment.
Study 3 Significant cueing effects were demonstrated, as in Study 1. Anodal and cathodal tDCS had an effect on probability cueing, with both stimulation groups outperforming Sham tDCS as demonstrated by a reduction in the overall number of inspected locations on cued trials. This suggests that right parietal cortex may play a role in learning [HA1] the probability cue in a small-scale virtual environment, and may contribute to the planning of search-related movements. Future experiments should investigate the role of the right parietal cortex in probability cueing further, using other neurostimulatory or neuroimaging techniques.
Learning and Modulating Spatial Probabilities in Virtual Environments Amy L. Holloway1, Peter Chapman1, Alastair D. Smith2 1University
of Nottingham, Nottingham, United Kingdom; 2University of Plymouth, Plymouth, United Kingdom
BACKGROUND Visual search behavior, in simple two-dimensional arrays, is sensitive to the spatial statistics of target distributions. When the target appears with greater likelihood in one-half of the array, participants become faster at locating it, in comparison to when targets are located on the other (low-probability) side. This phenomenon is known as probability cueing, and appears to operate below a level of conscious awareness (i.e., participants do not report awareness of the distribution when probed after the task). In contrast, studies that have employed large-scale search paradigms, in which full-body movements are required to inspect locations, report that probability cueing is more complex, requiring a combination of stable spatial cues and, when successful, appears to be explicit in nature.
AIMS This research aimed to investigate whether probability cueing could be observed in a virtual environment—a threedimensional medium between visual and large-scale search. The immersive qualities of the environment were manipulated by changing the display size and visual aspects across two experiments. In the final experiment, we investigated whether spatial cueing could be modulated by applying transcranial direct-current stimulation (tDCS) to the right posterior parietal cortex.
METHODS Participants were required to search for a hidden target within a virtual arena, which was displayed on a computer monitor (Study 1) or within an environment simulator (Study 2). In Study 1, the environment consisted of textured walls and flooring. In Study 2, texture was replaced by solid colors (to reduce levels of simulator sickness in the more immersive environment). Participants were not informed that the target was more likely to be located on one side of the array than the other. In Study 3, participants firstly completed a set of baseline trials, followed by 15 min of 1 mA tDCS (anodal, cathodal, or sham) to the right parietal cortex, then two blocks of probability cueing trials on a computer monitor (the same as Study 1). In all experiments, participants were probed for awareness of the manipulation after testing.
RESULTS AND CONCLUSIONS Study 1 Significant cueing effects were demonstrated, as exemplified by reduced search times to targets on the cued side of space. However, participants not express any conscious awareness of the probability cue. This is in line with the visual search literature, suggesting that physical effort may be necessary for explicit learning of the probability cue.
Study 2 No significant cueing effects were found. The removal of textures in the environment may have decreased optic flow, making it difficult for participants to accurately update their spatial location, and represent target statistics, as they explored the Neuroergonomics. http://dx.doi.org/10.1016/B978-0-12-811926-6.00035-X Copyright © 2019 Elsevier Inc. All rights reserved.
201
202 SECTION | VI Entries From the Inaugural International Neuroergonomics Conference
environment. Future experiments in immersive environments should, therefore, systematically explore whether probability cueing is related to the level of contextual information present in the environment.
Study 3 Significant cueing effects were demonstrated, as in Study 1. Anodal and cathodal tDCS had an effect on probability cueing, with both stimulation groups outperforming Sham tDCS as demonstrated by a reduction in the overall number of inspected locations on cued trials. This suggests that right parietal cortex may play a role in learning [HA1] the probability cue in a small-scale virtual environment, and may contribute to the planning of search-related movements. Future experiments should investigate the role of the right parietal cortex in probability cueing further, using other neurostimulatory or neuroimaging techniques.