Cognitive Daily

Could all babies be synesthetes?

i-eca0cf2af9fc3ac4445c7dff7d8aab70-research.gifTake a look at the following movie. Your job is to identify which ball appeared to make the noise in the final frame. (click to play):

i-1cc76cf2c4a5cfe95309b014dfe9831d-1.jpg

If this seems confusing now, it should be cleared up by the end of this post. You can register your result in this poll:

Synesthesia, as we’ve discussed before, is a rare condition. Synesthetes are people who perceive stimuli presented in one mode (often corresponding to one of the five senses) with a different mode. It’s a remarkable ability, manifesting itself in a variety of different ways — seeing “auras” around friends, or associating a sound or even a taste or a smell with certain types of visual images.

But how do people become synesthetes? One intriguing explanation is that we all start out that way: as babies, the sensory organs activate areas all around our brains, and only as we grow older do we specialize, by “pruning” neural connections, so images are processed in the visual cortex, sounds in the auditory cortex, and so on. Synesthetes, in this model, fail to prune as many of those connections as normal individuals, and thus retain some of their infant perceptual abilities.

Catherine J. Mondloch and Daphne Maurer have developed a series of experiments to see if very young children might show some evidence of synesthesia.

First, they showed 30-month-olds pairs of animals or objects and made a sound from a central speaker. For example, one picture was an elephant and a lion. Either a lion’s roar or an elephant’s trumpet was played, and the child was asked to point to the animal that made the sound. This was done to make sure the children understood the task, and all of the children could repeat this task at least three out of four times, with different pictures each time.

For the actual test, the children were shown a pair of bouncing balls — one small and white, the other large and gray. The balls both bounced simultaneously. As the balls bounced, they made either a 256 Hz tone (Middle C), or a 512 Hz tone (one octave higher). This was repeated four times, alternating between the high tone and the low tone. Finally, the balls were shown bouncing with either the high or low tone and the child was instructed to point to the ball that made the sound. Eleven out of the 12 children said that the small white ball made the high-pitched tone or the large gray ball made the low-pitched tone.

In new experiments, the process was repeated, but varying only the size or the color of the balls. In one task, the balls were the same size, with one white and one gray. All twelve children said the gray ball made the low-pitched sound or the white ball made the high-pitched sound. In the second task, both balls were white, but one was bigger than the other. In this task the results were less clear-cut. It took 24 children to obtain a significant result: 19 of the 24 children said the larger ball made the low sound or the small ball made the high sound.

This result corresponds to responses by adult synesthetes: small, bright objects make high-pitched sounds, while large, dark objects make low-pitched sounds. Mondloch and Maurer point out that while their result is consistent with the hypothesis that all newborns are synesthetes, it doesn’t prove it. The research does, however, offer an intriguing glimpse into the nature of infant perception.

Mondloch, C.J., & Maurer, D. (2004). Do small white balls squeak? Pitch-object correspondences in young children. Cognitive, Affective, & Behavioral Neuroscience, 4(2), 133-136.

Comments

  1. #1 tom s
    May 26, 2006

    I’m no fan of belief in the paranormal, but I can’t resist noticing something here.

    The experience of auras, which has long been dismissed by scientists, may now become accepted because it has a scientific explanation. Instead of “there’s no evidence that anyone sees auras” the line is changing to “well, people do see auras but they aren’t paranormal”.

    It is interesting that the new explanation may lead scientists to believe reports they formerly dismissed as unreliable. A little selective, no?

  2. #2 Davis
    May 26, 2006

    A little selective, no?

    Not really, no. It’s pretty standard for out-there ideas to be dismissed until someone presents solid evidence for such an idea, or for a mechanism that underlies the idea. Continental drift didn’t get accepted initially, either; the discovery of a mechanism (plate tectonics) and the accumulation of overwhelming evidence turned that around. That’s how science works.

  3. #3 FhnuZoag
    May 26, 2006

    Hmm, a point to note is that there may be a reading left to right effect – the first sound heard is assigned to the left, and the second to the right. I suggest that a flipped version be also used to remove this possibility.

  4. #4 tom s
    May 26, 2006

    Davis – I take your point, but the one I’m making is a little different. In this case it is not ideas that were dismissed, but observations — albeit observations by non-scientists :-). That is, many scientists did not take the reported observation of auras as reliable, or even likely. Now that the auras can be explained, they are more prepared to accept the reported observations (with a different interpretation).

    I know the border between the theory and observation is less clear than we’d like — theory-laden facts and all that — but I’m old-fashioned enough to believe that there is a pretty clear border in many cases.

    To change your mind about observations, which is what seems to be happening here, is a bit different from changing your mind about a theory.

  5. #5 Matt McIrvin
    May 26, 2006

    Did scientists dismiss the idea that people were seeing the auras, or just that the auras represented an external physical phenomenon outside the viewer’s head, such as emanations of a special energy? Because I’ve only really seen skepticism about the latter, and it still seems well-placed. It’s long been known that perfectly sane people see all kinds of unusual things.

  6. #6 Matt McIrvin
    May 26, 2006

    …Also, synesthesia itself has been known of for a long time, so it’s not as if synesthetic “auras” were only recently given a scientific framework.

  7. #7 Dave Munger
    May 27, 2006

    Wow, isn’t this fascinating? Our results are essentially completely random — evenly divided between the three possible responses.

    But 12 out of 12 two-year-olds say that the white ball makes the high-pitched sound. It certainly does seem that infant perception is significantly different from adult perception.

  8. #8 boojieboy
    May 27, 2006

    Since somebody brought up auras, I couldn’t resist responding.

    A lot of the credulous acceptance of auras comes from “evidence” supplied by thoroughly discredited photographic processes such as Kierlian photography.

    The other test that skeptics have used has been to place people behind a screen barely out of sight of the “aura viewer”. If an aura as described in paranormal circles is a real phenomenon (external to the mind of the person seeing the aura) then it should be viewable when the rest of the person’s body is not.

    It isn’t. Auras don’t pass this test.

    Scientists don’t discount the idea that people *perceive* auras around people or what have you. Anyone who knows anything about visual perception understands that auras are possible, and could describe several ways that even NORMAL individuals could see auras (let’s start with afterimages, and then continue from there), it’s just that the aura itself is not a real, external phenomena. They exist only in the mind/brain of the perceiver, and thus can only be expected to be subject to the rules which govern mental/perceptual phenomena.

    Seems to me like synesthesia, as bizarre as it is, fits right in there. So don’t start warming up your line about how “first they laugh at you, then they fight you, then they say they knew it all along”

    BTW, Galton named it, so it’s been known to scientists for a long time. It’s only now that neuroscience has supplied a reasonable explanatory mechanism that synesthesia has received a lot of attention.

    Just my 2 cents, so take it or leave it.

  9. #9 tom s
    May 27, 2006

    Thanks for the interesting responses. It does seem like I oversimplified the question. I do still think there is a little something there, but am happy to accept the comments others made — especially those of Matt McIrvin.

    And regardless of the aura thing, I agree with Dave Munger that it is fascinating to see how “infant perception is significantly different from adult perception.”

    [As one final sign-off, however, I would note that some of the responses to me did seem to have a "talk to the non-scientist about how science works" tone. I've done several years of research science, and it puts my back up a bit :-)]

  10. #10 jay
    May 28, 2006

    this is all very speculative but… for me something dark would indicate it being more dense/heavier than a lighter object (if i can’t hold them to tast) and a smaller object is usually assumed to be lighter than a large object… and don’t heavy things make lower, louder sounds when you drop them?
    so that’s a very tenuous link between the two, but the question is whether this consistent effect is observed with senses which are less easily connected in the adult brain eg a taste and a sound. i know the senses can be connected – i get the principal of synesthesia – but are the effects always consistent with different people? even if a group of people can all hear a sound when tasting something, will they all hear the same kind of sound (as they appear to with this exp. connecting sight and sound)?

  11. #11 C. Callosum
    May 28, 2006

    I was surprised by the poll results as it seemed fairly obvious to me that the light ball would be correlated to the higher-pitched sound. It has often been commented on that many languages demonstrate “sound symbolism”. An example would be pairs of proximal and distal demonstratives (e.g. “this” and “that”, respectively) where the proximal demonstratives have a higher frequency than the distal demonstratives.

    Hungarian, for instance, has a whole series of word pairs that differ in this way: ez ‘this’, az ‘that’ [note that the a vowel is pronounced very low, a bit like the a in "father", not that in "dad"]; itt ‘here’, ott ‘there’, etc.

    This sort of correlation has been observed in many languages: words with a higher vowel pitch tend to be associated with smallness, lightness, and nearness, and similarly vice versa. I therefore assumed that the results of this survey would be heavily skewed towards the high pitch-lightness correlation. Evidently I was mistaken! Very very interesting results.

  12. #12 Wim L
    May 28, 2006

    The association C. Callosum descrbes occurred to me too (although I didn’t know about Hungarian, etc. — interesting!). This makes sense from a physical perspective, since small objects and short distances are more likely to be associated with high-frequency (short-wavelength) sounds, for purely physical reasons. But if this is the reason for the correlation in peoples’ perspectives, I would expect *adults* to have a more-correlated response, since they have had more experience with the physical world.