Psychologist Harry Harlow explored how early-life experiences through caregivers affect human development and behavior. The effects of physical comfort were studied through monkeys, for ethical reasoning. Twelve infant monkeys took place in the trial and were placed with surrogate mothers. The first surrogate mother was made of cloth to resemble a human caregiver with more physical connection, while the second surrogate mother was made with wire, which the monkeys liked less than the cloth mother. Each of the monkeys had equally direct contact with both surrogate mothers for a total of five months. The monkeys were placed in a scenario where they became frightened and another where they became curious, and the monkeys’ actions were recorded. The experiments were all recorded when monkeys had contact with the cloth mother, the wire mother, and when the monkeys were alone. The independent variables include: availability of contact with the surrogate mothers, experiment procedures, and the length of time of separations between the monkeys and the cloth mother or wire mother. Dependent variables include: the behavior of the monkeys, how the monkeys interacted with the surrogate mothers, which surrogate mother fed the monkeys, and the surrogate mothers themselves. There were more than a few major findings discovered through these trials—the most obvious finding being that every single monkey spent more time with the cloth mother rather than the wire mother—whether the cloth mother nursed the monkey did not matter. This finding, as well as the results of the scenario-based experiments led to the determination that all the monkeys found more comfort in the cloth mother than the wire mother. In addition, every monkey grew at the same rate of the other monkeys, however, the monkeys that were fed by the wire mother experienced indigestion after eating when the monkeys fed by the cloth mother did not experience any indigestion—this being a symptom of the psychological stress these monkeys experienced. As a matter of fact, some monkeys that were fed from the wire mother acted the same as if they had no mother taking care of them. Harlow applied these findings to humans and hypothesized that men can care for newborns at the same capacity as women, because comfort is more important than the ability to physically nurse a baby. Another important connection is the one between the wire mother and humans. In this trial, the outcomes of the monkeys being with the wire mother portrayed similarities as children with abusive or negligent parents, bearing more attention to babies who are abused.