Although the results of this study seem to indicate that feeding is not the most important factor that ties an infant to a caregiver, we cannot say anything definitive about attachment in humans based on this study. Because it would be unethical to conduct a similar experiment with human babies, it is impossible to predict the outcome with certainty. However, observations of human infants reveal that they can become attached to family members who seldom if ever feed them, including fathers, siblings and grandparents (Shaffer & Emerson, 1964). In addition, a study was done that offered an interesting similarity to Harlow's, which showed that toddlers, usually in the Western world, who sleep alone and experience frequent daytime separations from their parents, sometimes develop a strong emotional tie to a soft, cuddly toy or blanket. These objects of attachment are effective sources of security that seem to substitute for special people when such people are not available (Passman, 1987), yet such objects have never played an important role in feeding.