“Researcher examines how brain perceives shades of gray” ..is the headline (italics added)
From Psypost: http://www.psypost.org/2011/11/researcher-examines-how-brain-perceives-shades-of-gray-8061
…but the actual study was on how people perceive shades of grey (or gray, depending on which language you’re writing in).
I intended this to be a minor moan about mislabelling interesting psychological research, but it developed into a discussion of the nature of Life and Meaning itself (sort of): see the bit after BUT… below.
This is about the interesting perceptual problem that we see white things as being white, even in rather dim light, when they’re reflecting thousands of times less light than they do in bright light, and also very much less light than is reflected from black things in bright light, which still look really black, even though they’re actually reflecting lots of light back to us. We must be working to some kind of baseline – ‘what’s the grey level brightness here?’ – or maybe ratio – ‘I’ll see the brightest thing here as white, and anything 100 times less bright as black’ – or something, but I don’t think that’s been worked out.
The study referred to here is testing out the ‘ratio’ explanation, by asking people to estimate levels of brightness over a checkerboard with a very great range of levels of brightness.
Sarah Allred, an assistant professor of psychology at Rutgers–Camden […] conducted the research with Alan L. Gilchrist, a professor of psychology at Rutgers–Newark, and professor David H. Brainard and post-doctoral fellow Ana Radonjic, both of the University of Pennsylvania. Their research will be published in the journal Current Biology. [No further reference given]
Participants were asked to look at a 5×5 checkerboard composed of grayscale squares with random intensities spanning the 10,000-to-1 range. They were asked to report what shades of gray a target square looked like by selecting a match from a standardized gray scale.
If the visual system relied only on ratios to determine surface lightness, then the ratio of checkerboard intensities the participants reported should have had the same ratio as that of the black and white samples on the reflectance scale, about 100-to-1.
Instead, the researchers found that this ratio could be as much as 50 times higher, more than 5,000-to-1.
Sounds like good evidence against the ratio model, which is interesting, because it’s probably the most obvious explanation for how we do this. I’d be tempted to follow this up and find out more (it’s also interesting for a photographer, because understanding the difference between how we appreciate tones and contrast and how the much more ‘objective’ system of the camera sensor/digital representation/monitor or paper output system does it would help in getting things to look the way we want them to look, in spite of the fact that the world of light is wilder and more varied than either our eyes or the digital systems can really cope with. Playing around with all the sliders and controls in Photoshop can help to give some ideas of what the issues are).
…you may guess what I’m going to say next. Why is this represented as brain research, rather than people research? The researcher is quoted as saying:
She continues, “In addition, even though we used behavioral rather than physiological measures, our results provide insight into the neural mechanisms that must underlie the behavioral results.”
“even though we used behavioural rather than physiological measures”?! Good grief. Yes the neural mechanisms are (probably equally) interesting, and understanding them will extend our understanding of the, apparently less valuable, behavioural processes – but isn’t the only* reason we want to find out about the brain processes because the behaviour/experience is interesting/puzzling/maybe practically important? If we didn’t have all those puzzles of consciousness and complex behaviour, would anyone give a toss about the brain processes?
Now I’ve got going on this, I could take it further: what’s the root cause here? What’s driving the evolution and development of our brains? There can’t be evolutionary selection of brains: it’s not the tissue, or even the wiring (it’s not really wiring, of course, but that’s our late-20th century metaphor for whatever weird things are going on in there) which is selected: it’s actions in the world, which result in survival for long enough, and then success in mating, to produce viable, adaptive offspring – in other words, behavioural and psychological things†.
Now, brain processes may limit the range of adaptation possible: in Terry Pratchett’s books, trolls are fick because their silicon-based nervous systems don’t run as fast as carbon-based ones at Ankh-Morpork temperatures (any real-life examples?), and physiological changes may give behavioural advantages which pay off in evolutionarily useful behaviour – like trichromatic vision in primates, which is said to give us better ability to distinguish between ripe and unripe fruits (and therefore allows better nutrition) than the crappy old two-colour system allowed – but the physiology is only important, and only selected for, as it’s mediated through behaviour.
So there you go – it’s psychology which got us where we are now; the physiology was just dragged along as a necessary underpinning. It’s about time we started misrepresenting brain research as psychology, just to make it sound important, not the other way round.
*OK, some nerds might be interested in it for its own sake, just like some people like to speculate about prime numbers – and that kind of interest can sometimes be useful in the long term.
† I admit that some of the physiology can be adaptive in straightforwardly physiological ways: so the mutation which makes some people resistant to the malaria parasite clearly improves their ability to survive and reproduce without that effect being psychologically mediated or significant, but I don’t see that as applying to brain-based evolution.