Parents of five-month-old babies spend a considerable amount of time trying to make them laugh. Sure, these infants have their low moments, crying because they’re soiled, hungry, or bored, but a new study has suggested that they are far more likely to remember the happy times than the bad ones. Ross Flom of Brigham Young University was lead author of the paper, which was published in the journal Infant Behavior and Development.
“People study memory in infants, they study discrimination in emotional affect, but we are the first ones to study how these emotions influence memory,” Flom said in a press release.
Of course, determining what an infant remembers is a bit more complex than testing an older child or adult. Because researchers cannot ask the infant, they studied the babies’ eyes and recorded how long they looked at a particular object. The researchers sought to add emotional attachment to images, investigating whether or not that would influence retention.
The babies were positioned in a closed-off area where they could only view a TV screen. An adult appeared on the screen and spoke to the child. The facial expression and tone of voice by the adult was either angry, happy, or neutral. After the adult was done speaking, the image on the screen was replaced by a geometrical shape.
Following the training period, retention of the geometrical shapes were tested after a waiting period of 5 minutes and 1 day. The shapes learned in the study were presented side-by-side against a new shape. Eye movement was recorded and the researchers calculated how much time the babies spent looking between the shapes from the study versus those that are newly-introduced. It was predicted that the babies would spend more time looking at the new shape than the familiar one.
After the 5 minute waiting period, the infants preferred to look at the new shape compared to familiar shape associated with happy expressions. Shapes associated with neutral or angry voices were not were not as familiar to the infants, as they did not show any preference between the two shapes. However, the infants did prefer the novel shape to the familiar one tied to neutral voices during the 24-hour retention test.
“We think what happens is that the positive affect heightens the babies’ attentional system and arousal,” Flom explained. “By heightening those systems, we heighten their ability to process and perhaps remember this geometric pattern.”
As of right now, the mechanism behind this phenomenon is not known. It is also not known how long the memory of the shapes associated with happy voices will last. An unrelated study by a team at McGill University in Montreal recently found that memories of language patterns heard in the first year of life are retained in the brain years later, which could make it possible to blend the two concepts and use happy voices to try and boost memory. Further research could uncover implications for this research that could benefit the child later in life.
[Header image: Jeremy Salmon via Flickr, CC BY-ND 2.0]