Final answer:
Among the options provided by Fantz, infants have shown a clear preference to fixate the longest on the human face disk due to their innate attraction to faces, which is critical for their social development.
Step-by-step explanation:
In a study examining infants' visual preferences, Fantz discovered that infants tend to fixate most on human faces. This preference for human faces over other stimuli such as colored disks or patterns has been consistently observed in newborns and young infants. This is reflective of an innate mechanism where infants are drawn to faces, which is critical for social development and caregiver recognition.
While infants show some ability to perceive colors like red, their color perception is limited at birth and develops more fully in the months after birth. Yet even with limited color perception, the human face seems to have a unique attraction due to its complexity and relevance to an infant's social environment.
In summary, among Fantz's options for visual stimuli, infants would fixate the longest on the human face disk, demonstrating a clear preference consistent with their innate attraction to faces.