the error bar says

the error bar is a long-term subscriber to the Scientific American magazine. it's usually on the bar, absorbing the spillover from a bubbly pint of red ale.

this month, the magazine contains an interview with Dr Bosten from the University of Sussex in the UK. the journalist & the scientist discussed how people differ in their perception of colour. the background to the interview is a comprehensive 35-page review that Dr Bosten published last month in the journal Annual Review of Vision Science.

Bosten's review starts with the individual differences in the cells in our eye - the so-called rods & cones - that receive light & generate electrical signals in the optic nerve. loyal listeners to the error bar will recall our interview with Dr Christopher Taylor in episode #5 in which he explained how chickens may very well see the colour of the universe in very different ways to us humans.

but, as this new review makes clear, us humans also see the universe of colour in very different ways to each other. due to a relatively high frequency of mutations in the genes for colour vision, 2% of X-chromosomes are missing one of the colour genes, giving 0.01% of males mono-chromatic vision - like seeing in black & white. then about 6% of males & 0.5% of females have anomalous colour vision, a bit like the red/green colour vision deficienty. there is even evidence that some females have colour vision capabilities approaching the sophistication of birds.

unlike some written accounts of colour vision differences, however, Bosten continues past the retina, & up the geniculostriate pathway to the visual cortex - an important part of the brain involved in, err, vision.

& they do not stop there. what about the environment you live in? or the language you use to name colours? all affect the way that our brain perceives the light that enters the two holes in the front of our heads.

conclusion

a highly recommended read