An experimental group is the group in an experiment that receives the variable being tested. One variable is tested at a time. The experimental group is compared to a control group, which does not receive the test variable. In this way, experimental groups are used to find answers in an experiment.
1 At around 9 months of age, babies begin to pull themselves up to a standing position. 2  By 10 months of age, a baby should be able to grasp objects with thumb and forefinger.
In fact, by 3-4 months infants have color perception similar to adults (Adams, 1995). At 1 week, the infant can discriminate the desaturated red from gray At 2 months, the infant can discriminate the desaturated blue from gray What do babies hear? Hearing is the most mature sense at birth. In fact, some sounds trigger reflexes even without conscious perception. The fetus most likely heard these sounds in the womb during last trimester Sudden sounds startle babies-making them cry, some rhythmic sounds, like a heartbeat/lullaby put a baby to sleep.