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Aging, Spatial Disparity, and the Sound-Induced Flash Illusion.

DeLoss DJ, Andersen GJ - PLoS ONE (2015)

Bottom Line: However, neither younger nor older individuals showed any significant effect of spatial disparity on the sound-induced flash illusion.Reaction time data was also analyzed.As expected, older individuals showed significantly longer reaction times when compared to younger individuals.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of California Riverside, Riverside, California, United States of America.

ABSTRACT
The present study examined age-related differences in multisensory integration and the effect of spatial disparity on the sound-induced flash illusion--an illusion used in previous research to assess age-related differences in multisensory integration. Prior to participation in the study, both younger and older participants demonstrated their ability to detect 1-2 visual flashes and 1-2 auditory beep presented unimodally. After passing the pre-test, participants were then presented 1-2 flashes paired with 0-2 beeps that originated from one of five speakers positioned equidistantly 100 cm from the participant. One speaker was positioned directly below the screen, two speakers were positioned 50 cm to the left and right from the center of the screen, and two more speakers positioned to the left and right 100 cm from the center of the screen. Participants were told to report the number of flashes presented and to ignore the beeps. Both age groups showed a significant effect of the beeps on the perceived number of flashes. However, neither younger nor older individuals showed any significant effect of spatial disparity on the sound-induced flash illusion. The presence of a congruent number of beeps increased accuracy for both older and younger individuals. Reaction time data was also analyzed. As expected, older individuals showed significantly longer reaction times when compared to younger individuals. In addition, both older and younger individuals showed a significant increase in reaction time for fusion trials, where two flashes and one beep are perceived as a single flash, as compared to congruent single flash trials. This increase in reaction time was not found for fission trials, where one flash and two beeps were perceived as two flashes. This suggests that processing may differ for the two forms for fission as compared to fusion illusions.

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Interaction between beeps and speaker displacement.Mean response as indicated by speaker displacement and the number of beeps. Error bars indicated ± 1 standard error of the mean.
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pone.0143773.g004: Interaction between beeps and speaker displacement.Mean response as indicated by speaker displacement and the number of beeps. Error bars indicated ± 1 standard error of the mean.

Mentions: Response data was analyzed using an Age (2: Younger, Older) x Flashes (2: 1 flash, 2 flashes) x Beeps (2: 1 beep, 2 beeps) x Speaker Displacement (3: 0m, 0.5m, 1m) mixed analysis of variance. For any effects that violated sphericity we used Greenhouse-Geisser corrections. Original degrees of freedom are reported. As expected the number of flashes significantly influenced the perceived number of flashes (F(1,22) = 28.847, p < .001, see Fig 2). There was also a significant effect of beeps (F(1,22) = 308.02, p < .001, see Fig 2). The beeps showed a significant effect on the perceived number of flashes for both fusion, fission, and congruent trials (see Fig 3). There was greater accuracy for the two flash as compared to single flash trials when multisensory information was congruent. This effect was more pronounced for older as compared to younger adults because the older adults tended to underestimate the number of flashes in the unisensory two flash condition. A significant interaction between beeps and speaker displacement was also found (F(2,44) = 3.36, p = .044, see Fig 4). A simple effects analysis of speaker displacement split by number of beeps revealed that there was a significant effect of speaker displacement for trials with a single beep (F(2,32) = 4.268, p = .023). Localized analyses using paired two-tailed t-tests revealed a significant difference between the 0.5 meter speaker displacement and the 1 meter speaker displacement (t(16) = 2.90, p = 0.01), the difference between the 0 meter and 1 meter speaker displacements did not reach significance (t(16) = 2.05, p = 0.057). Surprisingly, the single beep had a stronger effect on responses with a 1 meter displacement as compared to 0.5 meters. At 0.5m there was a small, albeit non-significant shift towards a decrease in both the fission and fusion illusion. However, at 1m this shift showed a significant increase in the fusion illusion as compared to the 0.5m condition.


Aging, Spatial Disparity, and the Sound-Induced Flash Illusion.

DeLoss DJ, Andersen GJ - PLoS ONE (2015)

Interaction between beeps and speaker displacement.Mean response as indicated by speaker displacement and the number of beeps. Error bars indicated ± 1 standard error of the mean.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4664268&req=5

pone.0143773.g004: Interaction between beeps and speaker displacement.Mean response as indicated by speaker displacement and the number of beeps. Error bars indicated ± 1 standard error of the mean.
Mentions: Response data was analyzed using an Age (2: Younger, Older) x Flashes (2: 1 flash, 2 flashes) x Beeps (2: 1 beep, 2 beeps) x Speaker Displacement (3: 0m, 0.5m, 1m) mixed analysis of variance. For any effects that violated sphericity we used Greenhouse-Geisser corrections. Original degrees of freedom are reported. As expected the number of flashes significantly influenced the perceived number of flashes (F(1,22) = 28.847, p < .001, see Fig 2). There was also a significant effect of beeps (F(1,22) = 308.02, p < .001, see Fig 2). The beeps showed a significant effect on the perceived number of flashes for both fusion, fission, and congruent trials (see Fig 3). There was greater accuracy for the two flash as compared to single flash trials when multisensory information was congruent. This effect was more pronounced for older as compared to younger adults because the older adults tended to underestimate the number of flashes in the unisensory two flash condition. A significant interaction between beeps and speaker displacement was also found (F(2,44) = 3.36, p = .044, see Fig 4). A simple effects analysis of speaker displacement split by number of beeps revealed that there was a significant effect of speaker displacement for trials with a single beep (F(2,32) = 4.268, p = .023). Localized analyses using paired two-tailed t-tests revealed a significant difference between the 0.5 meter speaker displacement and the 1 meter speaker displacement (t(16) = 2.90, p = 0.01), the difference between the 0 meter and 1 meter speaker displacements did not reach significance (t(16) = 2.05, p = 0.057). Surprisingly, the single beep had a stronger effect on responses with a 1 meter displacement as compared to 0.5 meters. At 0.5m there was a small, albeit non-significant shift towards a decrease in both the fission and fusion illusion. However, at 1m this shift showed a significant increase in the fusion illusion as compared to the 0.5m condition.

Bottom Line: However, neither younger nor older individuals showed any significant effect of spatial disparity on the sound-induced flash illusion.Reaction time data was also analyzed.As expected, older individuals showed significantly longer reaction times when compared to younger individuals.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of California Riverside, Riverside, California, United States of America.

ABSTRACT
The present study examined age-related differences in multisensory integration and the effect of spatial disparity on the sound-induced flash illusion--an illusion used in previous research to assess age-related differences in multisensory integration. Prior to participation in the study, both younger and older participants demonstrated their ability to detect 1-2 visual flashes and 1-2 auditory beep presented unimodally. After passing the pre-test, participants were then presented 1-2 flashes paired with 0-2 beeps that originated from one of five speakers positioned equidistantly 100 cm from the participant. One speaker was positioned directly below the screen, two speakers were positioned 50 cm to the left and right from the center of the screen, and two more speakers positioned to the left and right 100 cm from the center of the screen. Participants were told to report the number of flashes presented and to ignore the beeps. Both age groups showed a significant effect of the beeps on the perceived number of flashes. However, neither younger nor older individuals showed any significant effect of spatial disparity on the sound-induced flash illusion. The presence of a congruent number of beeps increased accuracy for both older and younger individuals. Reaction time data was also analyzed. As expected, older individuals showed significantly longer reaction times when compared to younger individuals. In addition, both older and younger individuals showed a significant increase in reaction time for fusion trials, where two flashes and one beep are perceived as a single flash, as compared to congruent single flash trials. This increase in reaction time was not found for fission trials, where one flash and two beeps were perceived as two flashes. This suggests that processing may differ for the two forms for fission as compared to fusion illusions.

Show MeSH
Related in: MedlinePlus