Friday, December 09, 2005

Influences of Temporal Fluctuation on Infant Attention

In the auditory world of human life, the events that occur and how we as listeners react to them, is based entirely on predictability. Whether listening to a Mozart Sonata, a clock ticking, or a bell chiming every hour, we hear these different events based on their being predictable or not. The article puts it simply enough, “A soothing lullaby exemplifies a highly predictable event…a sudden exclamatory vocalization exemplifies a relatively predictable event.”
The article by Nakata and Mitani describes an experiment which tests infant attention based on the regularity and irregularity of controlled sounds. Before the experiment is described the authors mention numerous examples from various works dealing with reactions to sound sequences when dealing with infants. For instance, infants have the ability to detect subtle “auditory events,” like differences in the time between “brief tones” (Trehub, Schneider, and Henderson). Also, infants are said to be able to detect acceleration from a constant sound and tempo sequence of an intermediate tempo if the ending tempo is 15% faster than the original (Baruch and Drake).
The article goes on to discuss information dealing with the ability of adults and infants to differentiate meter-preserving and meter-violating musical patterns. American adults could tell a difference in simple meters that had disturbances, but not in complex meters (often found in music of Eastern Europe, Middle East, Africa, and South Asia). Adults from Bulgaria and Macedonia who are familiar with simple and complex meters were able to hear the violations in both meters. Oddly enough, American infants, who had little contact with western and eastern music, were also able to hear the disturbances contained in both the simple and complex meters. (Hannon and Trehub)
The last topic before the experiment discusses “infants’ responsiveness to the maternal speech style.” First they mention adult directed speech, normal talk, and infant directed speech, baby talk. Many feel that babies are more likely to pay attention to infant speech because of the exaggerated pitches and contour lines (Fernald and Kuhl), but further research reasons that babies have no preference of adult directed versus infant directed based on pitch modulation alone (Colombo and Horowitz). They hypothesized that the rhythm of infant directed speech plays an important role in keeping the infants’ attention. Next, they described different ideas dealing with maternal singing opposed to maternal speech. An experiment by Shenfield, Trehub, and Nakata provided evidence to suggest that singing increases the level of health and lowers stress in infants. The last idea by Drake and Bertrand says that humans are predisposed to consistent sound based on internal oscillations and expectancies of future events.
The second half of the article addresses the experiment. Nakata and Mitani decided to test attention towards regular and irregular sound sequences for infants in two age groups, 6-8 months and 9-11 months old. They theorized that regular sound sequences would keep the attention of both age groups and irregular sequences which require more cognitive thinking would keep the older infants’ attention better than the younger infants’ attention. They made sure to note that all infants were healthy, free from congestion or ear infections, and had no family history of hearing loss to assure that all children had good hearing ability that would not skew the results. The participants consisted of 17 infants between 6 and 8 months of age and 15 infants between 9 and 11 months. An iBook computer was used to present visual and audio stimuli for the participants. The main stimuli consisted of a sound sequence, sounding similar to a xylophone tone, each sequence lasting 30 seconds in length, either a regularly occurring tone sequence or an irregularly occurring sequence. The visual stimulus was needed so that the infants would link the sound to the image allowing the testers to recognize and record the time that the infants were looking at the image (listening to the music), and not listening. The results found that younger infants looked longer at the regular sequence in the last five trials versus the first 5 trials but lost interest in the irregular sequence, having shorter listening times in the last 5 trials. The older infants had similar regular and irregular looking times with both decreasing from the first 5 trials to that last 5.
In conclusion, the authors were correct in certain portions of their hypothesis. They guessed that the regular sequence would hold infants’ attention longer than the irregular sequence. For younger infants, this was exactly true with their attention to regular increasing and irregular decreasing. On the other hand, older infants’ attention to the differing sequences stayed the same, decreasing in both tests. The younger infant results make sense based on studies dealing with motor development which show that regularity is very important at 6 months. Infants are said to kick at regular intervals until about 6 months.
The article goes on further to mention a study by Deckner, Adamson and Bakeman, stating that “rhythmic maternal vocalizations were associated with good infant language outcomes.” Experiments on auditory temporal patterns and attention still have much more research to carry out, controlled tests to run, and outcomes to analyze.


Blogger violinbrunetka said...

You have good wording. I enjoyed your presentation.

Friday, December 09, 2005 9:24:00 PM  
Blogger TheloniusFunk said...

When you refer to the article putting across a point well, you don't have to actually say, 'the article said this well..." just say it

Friday, December 09, 2005 10:30:00 PM  
Blogger mavoix said...

You seemed to explain things well in your article, but perhaps at the beginning you could have been a bit more clear on what you meant by we react to sounds by their predictibility part.

Friday, December 09, 2005 11:32:00 PM  
Blogger Annie said...

The information was great-- but when you're presenting something- make sure you aren't fidgeting- makes it appear as though you're nervous, and can be distracting.

Saturday, December 10, 2005 12:10:00 AM  

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