empty thoughts VII

7. Prepare for a long wind...

Experiment I: I wonder why the experimenters didn’t comment on the distance the animals maintained from each respective speaker. This seems like it would be a factor in sound-side preference because at the apex of the V-apparatus, sound waves from both high and low amplitude sound could be experienced to the same degree. So if an animal lingered near the apex of the V-apparatus it would suggest that the animal prefers a mixture of the two frequencies. However, if animals tended to spend more time at the tips of the V-arms, it would indicate a more selective preference for a particular sound amplitude over the other. It makes perfect sense that animals would prefer softer sounds, and when trained to expect that softer sound to come from a particular arm of the V-apparatus they would spend more time in that arm in the session directly following the sound-side switch. The observation that animals switched arms in order to spend more time in proximity to the soft sounds speaks to the integrity of the apparatus. It shows that animals were clearly making a sound-preference and are able to re-orient themselves relative to that sound preference.

Experiment II: Because the experimenters used the same animals for the distress call experiment as the loud/soft experiment, I think it was a good choice to test them with loud/soft stimuli first. Had animals been tested with distress/feeding sounds first, and the soft sound happened to be played from the same V-arm as a distress call, the animals may have shown preference for loud amplitude which would have been associated with the same arm as the feeding call, which would have hindered the validity of the results. It is interesting that animals do not show as drastic a preference between distress/feeding calls as between loud/soft calls. I think this may be an artifact of having been previously tested with loud/soft calls, because it seems contrary to evolutionary survival to have a sharper preference with regard to random loud/soft amplitudes than to distress/feeding amplitudes, as the latter distinction is far more ecologically relevant to survival than the former.

Experiment III: The data from this experiment are fascinating. What if the preference of humans for consonant sounds comes from the parameters of sound frequencies in our language? Especially because these participants were all (presumably) English-speaking - or at least Latin-derived language speaking – it seems that in our language, the tones we produce in sequence (sentences and longer) may have something to do with this preference. For instance, other languages which are not Latin-derived may use vowels or consonants in dissonant combinations, whereas English tends to have a very consonant flow between letters, words and phrases. Whereas tamarins, because they do not have a language of distinct vowels and consonants, but of variations in sound frequency, may not have a preference between consonant and dissonant sounds because these are both part of their typical language. I REALLY, REALLY WANT TO SEE THIS EXPERIMENTAL DESIGN USED TO COMPARE DIFFERENT LANGUAGE SPEAKING HUMANS TO ANY OTHER ANIMAL.

Experiment IV: As in experiment III, it seems likely that an explanation for the lack of preference between screech/noise control in tamarins might have something to do with their language. Humans do not communicate with screeching noises and in fact the only populations of us who seem to enjoy them are punk-metal emo kids. Tamarins, on the other hand, and many other primate species seem to use screeching variables in their communication patterns, which seems an important explanation for their lack of preference in this experiment.

As a whole, I really like this experiment design and the questions that it is addressing. It somewhat reminds me that solid research in the realm of evolutionary cognition is being done (which as you may have noticed, has thus far been forgotten...). However, I’m sorely disappointed with the lack of creative discussion of the implications of their results (as usual). There is such a huge window of consideration opened by this research about sound preferences and their correlations with behavior, language and evolutionary divergence in humans and non-human primates.

(McDermott and Hauser 2004)