The role of movement in the development of joint visual attention

Two experiments involving a training paradigm examined the role of adult head movement in early gaze following. In the first experiment, three groups of 9-month-old infants interacted with an adult, who, over a series of trials, presented one of two cues for the appearance of an interesting sight to the side. Two of the groups (nonspontaneous) were composed of infants who were not engaging in gaze following at the start of the session. One group saw the adult produce a head-rum movement to the side; the other saw only the static head orientation at the end of the same movement. The third group (spontaneous), composed of infants who were engaging in gaze following at the start of the session, also saw the adult's static head orientation. Results showed that nonspontaneous infants could learn to follow the dynamic head turn, but not the static head orientation. Spontaneous infants did follow the static head orientation. Given this result, a further group of nonspontaneous 9-month-olds were tested. Using the same paradigm, these infants observed the head-turn movement without the final static head orientation. They also followed gaze at above chance levels. The second experiment involved the same design and procedure as the first, with the exception that a head-tilt movement was substituted for the static head orientation. Again, nonspontaneous infants acquired gaze following with the head rum, but not with the head tilt. Spontaneous infants were able to learn the signal value of the head tilt in the experimental session. A further group of nonspontaneous 9-month-olds was tested in the same paradigm. These infants observed an adult head turn that stopped before reaching the target at 30 degrees. These infants also were able to learn to turn toward the correct target. These results are discussed in the context of the developmental origins of the gaze-following response necessary for joint visual attention and the infant's understanding of attention.