The Un-trained Ear

Language acquisition was the theme of our lecture this week, and the unbounded linguistic potential of infants was an important topic.  Examining broad theories of language acquisition, we first discussed Chomsky's ideas of the "Language Acquisition Device."  What he believed to be human's innate, biologically based mental structure for the acquisition of language.  This was contrasted with Bruner's theory of the Language Acquisition Support System (LASS); the idea that language develops only in a social context, guided and supported by parents and other caregivers.

One important example introduced within this theoretical clash was Janet Werker's study of phonological perception in infants (Developmental Aspects of Cross-Language Speech Perception

Janet F. Werker, John H. V. Gilbert, Keith Humphrey and Richard C. Tees, Child Development Vol. 52, No. 1 (Mar., 1981), pp. 349-355 ).  

Werker studied infants from non-Hindi speaking families and measured their abilities to discriminate a phoneme present in Hindi but not present in English.  You can listen to the difference between these phonemes in this online Hindi lesson.  A Phoneme is the smallest unit of sound within a language that can convey meaning.  Although there are hundreds of phonemes possible, each language uses its own select and limited sample to construct its phonology.  

In both longitudinal and cross-sectional studies, Werker found that infants at ages 6-8 months were able to recognize the difference between the two sounds, but that by 8-10 months, infants from non-Hindi speaking families had lost the ability to discern the Hindi phonemes.

Theoretically, this seems to support Chomsky's ideas, as we see that infants have an innate and almost unlimited ability to listen and discern differences in phonetic sounds.  As for Bruner's Social-cultural theory, in the limited case phonological discrimination, it seems that the Language Acquisition Support System is more destructive than constructive.  The child's social surroundings reinforce only the phonological productions of their native language, and the child's broad ability to discern the entire breath of human phonology withers away.

I had more than a merely academic interest in this topic, especially since Werker's study focused on Hindi.  As I have mentioned in a previous post, my wife is from India.  Although she is most comfortable speaking English, she is fluent in Hindi as well.  I know only a few words of Hindi.  As we raise our two children here in the US, we are always mindful of how to keep them in touch with their Indian heritage.  Language, of course is integral to this process.  

Our oldest child is 5, and has already passed the "sensitive period" where he could have learned to discriminate all of the sounds of Hindi.  I'm doubtful that he heard the language regularly and often enough to learn them.  He has also just begun kindergarten, and his wholehearted commitment to English phonology in concert with his efforts to learn to read make him resistant to other sounds.  Our daughter, on the other hand, is just turning 6 months old.  She is right in the middle of the sensitive period that Werker describes, where all phonological sounds are still distinct in her un-trained ear.  Unfortunately, all the pressure is on my wife to impart this ability to her.  As I never learned Hindi in my youth, I can't discriminate the sounds, nor can I re-create them accurately.     

Cross-race Identification Bias

Our lecture for this week on Perceptual Development had an interesting aside about a subject known as Cross-race Identification Bias.  This concept describes how people of a certain race often have a difficult time distinguishing between individuals of another race, and also have more difficulty recognizing the emotions of people of other races. 



This concept is an important part of perceptual development, particularly in terms of the development of the Fusiform Face Area (FFA) of the brain.  Human children are uniquely able to focus on and identify facial features from a very early age.  Development and utilization of the FFA is integral in this developmental capacity.

There is a downside to this process, however.  As with many other aspects of neurological development, our brain tends to become streamlined for simpler and faster processing.  When a baby grows up exclusively (or almost exclusively) seeing only faces of its own race, the FFA begins to specialize in recognizing the facial features and emotions of this race.  People are therefore able to more holistically identify features and emotions from people of their own race, but must rely on other more conscious (and fallible) mental processes to recognize features and emotions for people of other races.

Other social psychology studies have attributed this phenomenon to the In-group/Out-group effect, meaning that individuals view other people of the same race as members of their In-group and are more motivated to focus on and recognize their faces than people of another race, the Out-group. 

The concept of Cross-race Identification Bias is interesting as an academic subject, but it is of course also vitally important to many day-to-day aspects of life in our multi-racial, multi-cultural society.  Probably most important is its role in the criminal justice system and the reliance on eyewitness testimony.  This has often led to suspects being incorrectly identified by witness of other races and wrongly prosecuted and imprisoned.  African-Americans have been disproportionately affected by this tendency to racial bias in eyewitness reporting.

Speaking from my own experience as a Caucasian American, I can admit that this bias is definitely a problem for me.  I grew up in a very small and very racially homogenous town.  Today, living in a predominately African-American neighborhood, I have had several instances where I haven't recognized people that I had encountered several times.  On one occasion I actually passed a person on the street without recognizing them, and afterward realized that I hadn't even really looked at their face.

I have also often noticed myself being on the receiving end of this bias, however.  In my travels, I have often been mis-identified by locals of different countries, or not remembered by people I had talked to relatively recently.  I lived and studied in China for approximately a year and it was often obvious to me that for many Chinese, all white people looked alike.  I was often compared to many American celebrities that I didn't resemble in the slightest (even with different hair and eye color) simply because of the color of my skin.  Similar awkward situations often arise on travels to India to visit my wife's family.

More recently, my family lived in Tanzania for approximately 2 years, and local Tanzanian people would often confuse me with other white men.  Often times I would be approached by people who would begin talking as if they knew me and mentioning past conversations.  When I explained that I'd never met them or never been to that place, I could see the confusion on their face, gradually replaced by embarrassment. 

It wasn't always so harmless, however.  On one occasion I nearly had my car impounded because a parking enforcement officer insisted that I had sped off without paying for parking the day before and described an event in detail that I hadn't been there for.  It was obvious that she was confusing me with another Caucasian man from the same organization (with a very similar car), even though this man was 15 years older than me, balding and 6 inches shorter. 

 

I'm curious how this bias will play out for my son.  He is bi-racial (Caucasian and Asian Indian) and has been raised in areas where the majority of the population was black (Flatbush, Brooklyn and Tanzania).   Some studies have shown that increased exposure to other races can increase the accuracy of cross-race facial recognition. 

Experiment On Your Kids

Now that I have your attention with my sensationalistic title, let me tell you how I did a small (and absolutely harmless, I promise) study on my infant daughter.

Our lecture for this week was on Perceptual Development, and a special part of the lecture was devoted to explaining how psychologist has learned to study infants and their development.  As the lecture describes, early concepts of infant development saw them as passive "blank slates" who did not interact with their environment in any meaningful way.  This was because infants were mostly observed and measured on child or adult standards that relied heavily on motor coordination beyond an infant's capacities.  Psychologist eventually developed ways to study infants, however, and learned of their complex sensory lives.

One important method was to carefully observe infants and measure their eye movements or looking, along with sucking rates and heart rates.  This type of observation is then paired with studies of Habituation and Dis-habituation.  Habituation refers to that fact that when repeatedly presented with the same stimuli, infants will lose interest and pay attention to it for shorter and shorter amounts of time.  Dis-habituation occurs when the infant is then presented with a new or novel stimuli.  The infants response to the new stimuli, usually measured by how long the infant pays attention, can then be compared.  For studies of visual perception, this is usually done by observing and timing the infant's gaze on various images.

For my own little study, I used my 5 month old daughter.  I presented here with a toy she wasn't familiar with (one of her brother's toys) and watched how long she stared at it.  Here's a picture of the toy:


I thought this would be a good object to use to test for her attention because it has a face shape on it, and, as we have learned this week, infants are pre-disposed to seek out human faces.  As one would commonly predict, my daughter was very interested in the toy at first, staring for 7-8 seconds.  But after several viewings, she had little interest in it and completely stopped looking.

As you might notice from looking at the toy, however, it is a spring and can stretch out to this shape:




When I showed my daughter the stretched out shape of the toy, she immediately regained interest and stared intently for 8-9 seconds.  An interesting aspect of the toy when stretched out is that the face shape becomes distorted.  It is divided into segments and stretched out.  If stretched out long enough, the face becomes unrecognizable.  It seemed that even though my daughter initially showed great interest in the stretched out shape of the toy, she seemed to habituate to it even faster than the contracted shape.  Perhaps this fact displays a novel example of infant's preference for human faces, even over novelty in shape.  Even though the novelty of the new shape was interesting, perhaps the distortion caused in the face shape when stretched out caused her to have less overall interest.