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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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Related in: MedlinePlus

Experimental Layout.The experimental layout including the participant, monitor and speakers.
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pone.0143773.g001: Experimental Layout.The experimental layout including the participant, monitor and speakers.

Mentions: The experiment consisted of the two pre-tests and a single experimental block. The entire experiment took approximately 1 hour. The experimental block assessed participants’ ability to discriminate 1 to 2 visual flashes when paired with 0–2 beeps. The beeps came from one of five speakers placed 100 cm from the observer along a semi-circle (see Fig 1). This configuration was used to control for the effect of distance. All speakers were calibrated so that the beeps were presented at 72dB at the observer. Each possible combination of flashes, beeps and speaker displacement was presented 20 times during the experimental block, for a total of 560 trials. Presentation order was randomized for each participant. The task of the participant was to report the perceived number of flashes using the left and right arrow keys, with the left arrow key indicating one flash and the right arrow key indicating two. Participants were informed that the trials would frequently be accompanied by a series of beeps, and that while these beeps may be distracting to remember to respond only to the number of flashes presented. On each trial participants fixated on a 0.5° white crosshair presented 2.5° above the center of the screen that was presented for 250–1250 ms randomized on each trial. This variable onset timing was implemented to eliminate any strategy using the temporal length of each trial as a cue to the number of flashes presented. After the delay 1–2 visual flashes were presented 5° below the fixation cross. The crosshair then disappeared and text appeared on the screen instructing the participants to “Please enter ← if you saw one flash or → if you saw two flashes.” Participants then entered their response.


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

DeLoss DJ, Andersen GJ - PLoS ONE (2015)

Experimental Layout.The experimental layout including the participant, monitor and speakers.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0143773.g001: Experimental Layout.The experimental layout including the participant, monitor and speakers.
Mentions: The experiment consisted of the two pre-tests and a single experimental block. The entire experiment took approximately 1 hour. The experimental block assessed participants’ ability to discriminate 1 to 2 visual flashes when paired with 0–2 beeps. The beeps came from one of five speakers placed 100 cm from the observer along a semi-circle (see Fig 1). This configuration was used to control for the effect of distance. All speakers were calibrated so that the beeps were presented at 72dB at the observer. Each possible combination of flashes, beeps and speaker displacement was presented 20 times during the experimental block, for a total of 560 trials. Presentation order was randomized for each participant. The task of the participant was to report the perceived number of flashes using the left and right arrow keys, with the left arrow key indicating one flash and the right arrow key indicating two. Participants were informed that the trials would frequently be accompanied by a series of beeps, and that while these beeps may be distracting to remember to respond only to the number of flashes presented. On each trial participants fixated on a 0.5° white crosshair presented 2.5° above the center of the screen that was presented for 250–1250 ms randomized on each trial. This variable onset timing was implemented to eliminate any strategy using the temporal length of each trial as a cue to the number of flashes presented. After the delay 1–2 visual flashes were presented 5° below the fixation cross. The crosshair then disappeared and text appeared on the screen instructing the participants to “Please enter ← if you saw one flash or → if you saw two flashes.” Participants then entered their response.

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