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Long-Duration Spaceflight Increases Depth Ambiguity of Reversible Perspective Figures.

Clément G, Allaway HC, Demel M, Golemis A, Kindrat AN, Melinyshyn AN, Merali T, Thirsk R - PLoS ONE (2015)

Bottom Line: The reaction time decreased throughout the sessions, thus indicating a learning effect.However, the time to first percept reversal and the number of reversals were not different in orbit and after the flight compared to before the flight.These results indicate that the perception of "illusory" depth is altered in astronauts during spaceflight.

View Article: PubMed Central - PubMed

Affiliation: Lyon Neuroscience Research Center, Bron, France.

ABSTRACT
The objective of this study was to investigate depth perception in astronauts during and after spaceflight by studying their sensitivity to reversible perspective figures in which two-dimensional images could elicit two possible depth representations. Other ambiguous figures that did not give rise to a perception of illusory depth were used as controls. Six astronauts and 14 subjects were tested in the laboratory during three sessions for evaluating the variability of their responses in normal gravity. The six astronauts were then tested during four sessions while on board the International Space Station for 5-6 months. They were finally tested immediately after return to Earth and up to one week later. The reaction time decreased throughout the sessions, thus indicating a learning effect. However, the time to first percept reversal and the number of reversals were not different in orbit and after the flight compared to before the flight. On Earth, when watching depth-ambiguous perspective figures, all subjects reported seeing one three-dimensional interpretation more often than the other, i.e. a ratio of about 70-30%. In weightlessness this asymmetry gradually disappeared and after 3 months in orbit both interpretations were seen for the same duration. These results indicate that the perception of "illusory" depth is altered in astronauts during spaceflight. This increased depth ambiguity is attributed to the lack of the gravitational reference and the eye-ground elevation for interpreting perspective depth cues.

No MeSH data available.


Related in: MedlinePlus

Reaction time.Duration between stimulus onset and the first response for all 6 figures for 6 astronauts across pre-flight (L-day), in-flight (FDday), and post-flight (R+day) sessions. Mean (black symbols) and median (horizontal lines) with 50th-percentile ranges (boxes) and 90th-percentile ranges (between whiskers); * p < 0.05 relative to L-220. The grey box-and-whisker plots show the responses for 14 control subjects.
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pone.0132317.g004: Reaction time.Duration between stimulus onset and the first response for all 6 figures for 6 astronauts across pre-flight (L-day), in-flight (FDday), and post-flight (R+day) sessions. Mean (black symbols) and median (horizontal lines) with 50th-percentile ranges (boxes) and 90th-percentile ranges (between whiskers); * p < 0.05 relative to L-220. The grey box-and-whisker plots show the responses for 14 control subjects.

Mentions: During the tests performed on the ground, the reaction time was not significantly different between the control subjects and the astronauts [(F (1,359) = 3.38, p = 0.07]. A repeated-measures ANOVA in the control subjects’ data yielded a significant difference in reaction time across the 3 test sessions [F (2,234) = 5.92, p = 0.003] and the 6 figures [F (5,234) = 6.72, p < 0.001] but no interaction between the two [F (10,234) = 0.88, p = 0.82). A repeated-measures ANOVA in the astronauts’ data also yielded a significant difference in reaction time across the 10 test sessions [F (9,300) = 8.83, p < 0.001] and the 6 figures [F (5,300) = 9.50, p < 0.001] and no interaction between the two [F (45,300) = 1.20, p = 0.19). The reaction time decreased significantly between the first and the third session for the control subjects (paired t-test, p = 0.001) and with the repetition of the tests in-flight and post-flight for the astronauts (Fig 4).


Long-Duration Spaceflight Increases Depth Ambiguity of Reversible Perspective Figures.

Clément G, Allaway HC, Demel M, Golemis A, Kindrat AN, Melinyshyn AN, Merali T, Thirsk R - PLoS ONE (2015)

Reaction time.Duration between stimulus onset and the first response for all 6 figures for 6 astronauts across pre-flight (L-day), in-flight (FDday), and post-flight (R+day) sessions. Mean (black symbols) and median (horizontal lines) with 50th-percentile ranges (boxes) and 90th-percentile ranges (between whiskers); * p < 0.05 relative to L-220. The grey box-and-whisker plots show the responses for 14 control subjects.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4492703&req=5

pone.0132317.g004: Reaction time.Duration between stimulus onset and the first response for all 6 figures for 6 astronauts across pre-flight (L-day), in-flight (FDday), and post-flight (R+day) sessions. Mean (black symbols) and median (horizontal lines) with 50th-percentile ranges (boxes) and 90th-percentile ranges (between whiskers); * p < 0.05 relative to L-220. The grey box-and-whisker plots show the responses for 14 control subjects.
Mentions: During the tests performed on the ground, the reaction time was not significantly different between the control subjects and the astronauts [(F (1,359) = 3.38, p = 0.07]. A repeated-measures ANOVA in the control subjects’ data yielded a significant difference in reaction time across the 3 test sessions [F (2,234) = 5.92, p = 0.003] and the 6 figures [F (5,234) = 6.72, p < 0.001] but no interaction between the two [F (10,234) = 0.88, p = 0.82). A repeated-measures ANOVA in the astronauts’ data also yielded a significant difference in reaction time across the 10 test sessions [F (9,300) = 8.83, p < 0.001] and the 6 figures [F (5,300) = 9.50, p < 0.001] and no interaction between the two [F (45,300) = 1.20, p = 0.19). The reaction time decreased significantly between the first and the third session for the control subjects (paired t-test, p = 0.001) and with the repetition of the tests in-flight and post-flight for the astronauts (Fig 4).

Bottom Line: The reaction time decreased throughout the sessions, thus indicating a learning effect.However, the time to first percept reversal and the number of reversals were not different in orbit and after the flight compared to before the flight.These results indicate that the perception of "illusory" depth is altered in astronauts during spaceflight.

View Article: PubMed Central - PubMed

Affiliation: Lyon Neuroscience Research Center, Bron, France.

ABSTRACT
The objective of this study was to investigate depth perception in astronauts during and after spaceflight by studying their sensitivity to reversible perspective figures in which two-dimensional images could elicit two possible depth representations. Other ambiguous figures that did not give rise to a perception of illusory depth were used as controls. Six astronauts and 14 subjects were tested in the laboratory during three sessions for evaluating the variability of their responses in normal gravity. The six astronauts were then tested during four sessions while on board the International Space Station for 5-6 months. They were finally tested immediately after return to Earth and up to one week later. The reaction time decreased throughout the sessions, thus indicating a learning effect. However, the time to first percept reversal and the number of reversals were not different in orbit and after the flight compared to before the flight. On Earth, when watching depth-ambiguous perspective figures, all subjects reported seeing one three-dimensional interpretation more often than the other, i.e. a ratio of about 70-30%. In weightlessness this asymmetry gradually disappeared and after 3 months in orbit both interpretations were seen for the same duration. These results indicate that the perception of "illusory" depth is altered in astronauts during spaceflight. This increased depth ambiguity is attributed to the lack of the gravitational reference and the eye-ground elevation for interpreting perspective depth cues.

No MeSH data available.


Related in: MedlinePlus