Visually elicited reaching in neonates.
Infants aged 8-16 days were shown a small ball, a picture of a ball, and a homogeneous stimulus card. Their reaching behavior was scored for each stimulus condition. a reach was defined using the following 3 criteria: (1) lateral extension of the arm, (2) arcing movement of the arm toward midline, and (3) flexion of the arm toward the upper half of the body. The mean rates of reaching per minute for the ball, the picture, and the homogeneous or blank card were 2.94, 2.78, and 1.83, respectively. t tests showed significant differences between the ball and blank-card conditions (p less than .002) and between the picture and blank-card conditions (p less than .007), but not between the ball and picture conditions. Thus, arm movements resembling reaching can be visually elicited in neonates, but they are elicited as readily by 2-dimensional as by 3-dimensional stimuli. Furthermore, infants do not refrain from reaching when a large central area of their visual field is blank. These results suggest only that the probability of reaching-like behavior is increased by the presence of a patterned visual stimulus.
D000367:Age Factors; D001132:Arm / Q000502:physiology; D005260:Female; D006801:Humans; D007231:Infant, Newborn / Q000523:psychology*; D008297:Male; D009043:Motor Activity; D013028:Space Perception; D014796:Visual Perception