Over New Year’s I had a brief discussion with a condensed-matter physicist who proclaimed that 1) “some developmental research is amazingly bad” and that 2) “they think they can tell what a baby has learned from what direction it looks,” topping it all off with 3) “you guys don’t even know what learning is!”
I won’t argue with the first point (there are bad researchers in every field, even condensed matter physics), and I’m too lazy to bother with the third (although the 2000 Nobel prize committee might disagree), but the second point – on the technique of preferential looking – I just can’t disregard. Complaints about the rigor of developmental cognitive psychology are surprisingly common (e.g.), but all too often unjustified.
Using this comment about the preferential looking paradigm as an example, such complaints can be understood in several ways:
1) Conflating accessibility with lack of sophistication.
If a scientific technique can be easily understood, it might be mistaken as the tool of an unsophisticated, naive, or stupid scientist. This logical fallacy – “affirming the consequent” – arises from a bias common to fields where the quality of your data is directly related to the money you can spend on a device to collect it.
2) “Physicist’s disdain”
This is the disdain permitted of physicists towards other scientists, all of whom are presumed to have “physics envy”, a situation where “biologists kind of envy biochemists who kind of envy chemists who kind of envy physicists. Everybody wants to wear a slightly whiter coat.”
The focus of physicist’s disdain is inconsistent. Sometimes it lingers on the lack of complex mathematics in other disciplines; other times on that apparent uselessness stigmatizing any science which hasn’t yet dreamed up a new weapon of mass destruction. Most often, it lingers on the fact that all other sciences study higher-order phenomena – phenomena which can never be truly understood without the meticulous and back-breaking lower-order work of physicists. By this view, everyone really should be a physicist, and so envy is fully justified.
3) Lack of familiarity with the technique
This is both the most obvious and the most forgivable (as well as the most likely, in the case of my friend the physicist). It turns out that most developmental cognitive psychologists are not stupid, are therefore not unaware of the higher-order level of their inquiry, and thus have gone to much trouble to validate their methods.
It also turns out the preferential looking paradigm is a particularly poor choice for complaining about a lack of rigor, since extensive work over the past 40 years has confirmed that infant gaze is a wonderful indicator of varied perceptual and cognitive phenomena. For example, the preferential looking paradigm is sufficiently sensitive to detect amblyopia and other visual disorders in newborns, and is in fact a more clinically appropriate tool than “more sophisticated psychophysical techniques” which can bore babies due to their length. By some accounts, the technique has allowed for measurements of visual acuity in infants which are as precise as those in adult subjects, and reliability is quite high. Preferential looking is now a standard to which other neonatal ophthalmological methods are compared.
The preferential looking paradigm has also proven valuable in more cognitive domains. For example, infants older than 7.5-months discriminate between visual displays where memory for simple features is not enough, but where they must be integrated into complex objects. This capacity is known as “visual binding,” and addresses a longstanding problem in cognitive neuroscience.
Preferential looking has also been productively employed outside of the visual cognitive sciences, in an impressive testament to its generality. For example, only infants older than 3.5-months prefer faces whose gender matches that of a recorded voice, suggesting audio-visual integration; infants older than 6-months will preferentially gaze towards the faces/mouths with an articulatory posture matching an audio recording of a vowel, suggesting nascent audio-motoric integration; and gradations in gaze preference demonstrate that 8-month-olds may be capable of extracting abstract rules from auditory input structured by artificial grammars.
As in condensed matter physics, and probably all sciences, some discrepancies between various measurement techniques can be expected, exacerbated by lack of agreement on the proper controls. Debate over these issues is what characterizes an intelligent and mature science, not the accessibility of its measurement techniques to laymen.