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PERCEPTION OF THE FLASH-LAG EFFECT

PERCEPTION OF THE FLASH-LAG EFFECT. Maksims Ivanovs University of Tartu / University of Latvia Advisor: Jaan Aru. Introduction. The flash-lag effect: http ://www.michaelbach.de/ot/mot-flashLag/ index.html

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PERCEPTION OF THE FLASH-LAG EFFECT

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  1. PERCEPTION OF THE FLASH-LAG EFFECT Maksims Ivanovs University of Tartu / University of Latvia Advisor: JaanAru

  2. Introduction • The flash-lag effect: http://www.michaelbach.de/ot/mot-flashLag/index.html • Most likely caused by the neural delays in arrival of photoreceptor signals from retina to visual cortical areas • Threshold: 1 rpm / 2 rpm • Why it is important

  3. The Present Research • Purpose: to study possible effect of gender, age, education • Hypotheses • Gender has an effect on the threshold • Age has an effect on the threshold • Education has an effect on the threshold • Data gathering: a large-scale online survey

  4. Survey • The pilot study: 8 participants • Design: • 3 parts: introduction, the questions regarding the perception of the visual stimulus, the questions regarding the participants himself / herself • Two orders of the stimuli: • 10, 15, 5, 4, 3, 2, 1 rpm • 10, 5, 4, 3, 2, 1, 15 rpm • Three languages: English, Latvian, Russian • All in all – six versions

  5. Administering the Survey • Facebook, email • Personal contacts • Facebook groups: • ESN Tartu Spring 2014 • Neuroscience • Psychology • Forwarding via email to the students: • UT Faculty of Mathematics and Computer Science • UT Faculty of Philosophy • UL Faculty of Humanities • Key principles: • order of stimuli, gender, age, level of education

  6. Raw Data • N = 238 • 10, 15 … 1 rpm = 134 • 10, 5 … 15 rpm = 104 • Gender: • Males: 63 • Females: 175 • Age: group from 20-29 = 172 • Education: • Secondary school = 88 • Bachelor degree = 80 • Country of origin: 30 countries (Estonia, Latvia, Syria, Israel, Australia, etc.)

  7. Preliminary Processing of the Data • Invalid responses: • Don’t see any lines; • Inconsistent responses (5 rpm = Y, 4 rpm = N, 3 rpm = Y); • Not observing the effect at 15 rpm or 10 rpm • Normalisation of the responses: • The questions regarding the respondent • The questions regarding the perception of the stimuli

  8. Preliminary Processing of the Data • Normalisation of the responses to the questions regarding the perception of the stimuli: • Normalised = 3 • Not normalised = 24 • ‘when vertical or horizontal, they [lines] appear aligned; when at 45 or 135 degrees, the flashing line appears to lag slightly’ • ‘[the flashing line (or the first line!?)] sometimes lags a little behind, sometimes [is] aligned and sometimes [runs] ahead’

  9. Data • N = 175 • By gender: M = 51, F = 124

  10. Data Age

  11. Data Education

  12. Average threshold = 2,594 rpm • Bach = 1 rpm / 2 rpm

  13. M = 2,35 • F = 2,69 • Wilcoxon rank sum test: p = 0.064 • Not statistically significant, yet thereis a trend

  14. Spearman correlation test: rho = -.177, p < 0.025 • Weak negative correlation

  15. Kruskall Wallis test: p > 0.2 • No effect

  16. Conclusions • Fairly large sample • All respondents: 2,594 rpm vs 1 rpm / 2 rpm • Gender: trend rather than effect • Age: weak negative correlation • Education: no effect • Limitations of the research • Further study: • Sample distribution by gender • Sample distribution by age

  17. Thank you!

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