Hancock et al. (2006)

From Psy3241

Current revision as of 02:42, 29 April 2008

Monozygotic Twins' Colour-Number Association: A Case Study

  Presentation By Mandy French

Introduction

• Investigates the color-number associations of monozygotic twins age 12 at testing

• Origin of color-number association is known to be a colored number jigsaw puzzle

• At age 3 the association was first noted when a teacher asked the boys to report numbers, but they insisted on reporting color names

• The colors that were reported were synonymous with the colors shown on the “Early Learning Centre” number jigsaw puzzle that the boys regularly played with

• The brothers showed the same color to number pairings, but the association was not quit as strong for one of the brothers

• By age 12 the boys report what color a digit is as well as most letters

• Researcher was interested in determining if the boys show the Stroop-like interference effects that are commonly used and if they had enduring associations

Methods

• Name the color in which a digit is displayed

• Hypothesized that if the digit is colored according to the jigsaw puzzle, then the boys will be quicker when compared to incorrectly colored digits

Participants

• Monozygotic twin boys aged 12 years and 2 months

• Physically and intellectually similar

Materials

• The twins separately selected colors for each of the digits from 0-9

• Numbers were displayed in 200pt font about 6cm high on the screen

• The color selections the boys made were stored as congruent colors

• Incongruent versions were created by changing the colors of discordant pairs

• The swaps were all for adjacent numbers

Procedure

• Asked to name the color of the displayed digit as rapidly as possible

• Each digit was presented 8 times in one run of the experiment

• Each digit was presented 4 times congruent and 4 times incongruent per run

• Each boy ran the procedure 6 times over a couple of days

• A total of 24 trials were conducted for each digit

Results

• 49 of the 480 trials were removed for R and 51 were removed for T because the voice trigger failed to detect the word or was triggered by an extraneous noise

• 38 trials for R and 19 trials for T were removed because they were more than 2 standard deviations away from the mean

• Both boys had an increased reaction time to incongruent colors

• An Anova demonstrates an effect of congruence, but not a significant difference between the boys

• R made more color naming errors than T

• 11 errors for R and 1 error for T

• It is believed that T was more careful, which resulted in his lower error rate and slower reaction time

Discussion

• “Associator” Synaesthetes can see colors in the “mind’s eye”

• “Projector” Synaesthetes see the color as an overlay on the digit

• The boys experience is consistent with the finding that they do not report photisms or any sense of perceiving color, they just know that a particular number is a specific color

• Elias et al. showed the synaesthete showed much stronger activation in visual areas on several tasks than the learned associator

• It would be interesting to use fMRI to see in which group of synaesthetes the boys fit into

• The boy’s association is learned, but not practiced

• Both twins report the color-number association and do so with a very similar set of colors

• Even though both boys had not seen the jigsaw puzzle for at least 7 years at the time of testing, the accuracy of the match was remarkable

• It is estimated that the frequency of synaesthesia is 1 in 25,000

• Recent study demonstrates the possibility of the rate of synaesthesia being as high as 1 in 110

• Synaesthesia may not be an all or nothing effect, but may be more of a graded phenomenon with enduring associations at one end of the scale and full blown cross modal perception at the other

• R and T seem to fit at the mild end of the range

• R and T have reliable, long lasting associations that cause a Stroop interference, even though they do not report seeing anything

• A genetic effect for synaesthesia is possible because the boys’ mother also displayed a color-number association

Questions

Is it possible that if the twins practiced the learned association that the color-number association could grow stronger?

See also: Synesthesia