The Experiment
For this experiment, you’ll need 2 balls: a small one that Luka can easily grasp and hold with one hand and a larger one that Luka will need 2 hands to hold. Hold the small ball in front of Luka and note whether he reaches for it with 1 hand or both hands. Then hold the larger ball in front of him and again note whether he reaches for it with 1 or both hands. In each case, after he graps the ball, let him hold and play with it for about 30 seconds. Repeat the presentations until you can determine a reching preference: Does Luka prefer to reach consitently with a single or with both hands? If you are able to establish a reaching preference, you’ll then move to the next part of the experiment, during which you will present Luka with only the object whose size does not match his reaching preference. If Luka prefers to reach with 2 hands, repeatedly present the small ball and see whether he’ll switch to a 1-handed reach. If Luka prefers to reach with 1 hand, repeatedly present the larger ball and see whether he’ll switch to a 2-handed reach. Repeat these presentations about 10 times.
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Hypothesis
Despite repeated opportunities to grasp the small ball with 1 hand (or the larger ball with 2 hands), Luka will continue to sue his preferred reaching style. The younger the baby, the more likely he will be to persist with his established reaching preference.
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The Result
I think Luka is just too clever. Every time I presented him with the larger ball he immediately grabbed it with 2 hands:
And every time I gave him the small ball, he used 1 hand!
In fact he was so good with this game, you just have to watch this to see….
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The Science
A 2009 study presented 6, 7, 8 and 9-month-old babies with small solid balls (about 2 inches in diameter) and larger solid balls (about 5 inches in diameter) to determine a reaching preference. The vast majority of babies responded mainly with 2-handed reaching. A few preferred 1-handed reaching. And a small number showed no consistent preference, but instead varied their reaching style based on the size of the ball (go Luka!). Of those who showed a 1-handed preference, the majority continued to reach with 1 hand when they were repeatedly presented with the larger ball, adn of those who showed a 2-handed preference, the majority continued to reach with 2 hands when they were repeatedly presented with the small ball.
The researchers found that unlike adults, who can immediately adapt their reaching style based on their prior experience holding an object, infants in the age groups tested in this study had a difficult time overcoming their innate reaching preference, even after repeated exposures to the object. This suggests that the process of determining a method of reaching for an object that is appropriate for the object’s size is a protracted developmental process.
Fun With Luka & Tilen 