Harlow tested the importance of contact comfort versus nutritional reinforcement using infant rhesus monkeys and two surrogate 'mothers': one made of bare wire that provided milk, and one covered in soft cloth that provided no food.
The results revealed that monkeys spent the vast majority of their time (up to 18 hours a day) clinging to the cloth mother, only visiting the wire mother briefly to feed, especially when frightened.
This research proved that attachment is not merely a 'learned' behavior based on the association of the mother with food, but a biological need for physical warmth and security.
| Feature | Lorenz (Geese) | Harlow (Monkeys) |
|---|---|---|
| Primary Concept | Imprinting & Critical Period | Contact Comfort & Social Development |
| Mechanism | Visual/Movement Stimulus | Tactile/Physical Stimulus |
| Timeframe | Critical period of a few hours | Critical period of approximately 90 days |
| Long-term Impact | Sexual imprinting/Mate choice | Social competence and parenting ability |
While Lorenz focused on the immediate survival mechanism of following a protector, Harlow focused on the emotional and social foundations required for healthy psychological development.
Both researchers agreed on the existence of a critical period, but the duration and the consequences of missing it varied significantly between the avian and primate species studied.
Identify the Theory Challenged: Always mention that these studies were used to refute the Learning Theory (or 'cupboard love' theory), which argued that babies only love their mothers because they provide food.
Use Precise Terminology: Distinguish clearly between 'imprinting' (Lorenz) and 'contact comfort' (Harlow) to avoid losing marks for conceptual blurring.
Evaluate Ethics: In exams, these studies are often used to discuss ethical issues; be prepared to discuss the psychological harm to Harlow's monkeys versus the scientific benefits of the findings.
Generalization Warning: Be cautious when applying these findings to humans; while they provide insight, human attachment is significantly more complex and involves conscious cognitive processes.
The Food Fallacy: A common mistake is assuming Harlow's monkeys preferred the wire mother because she had food; they actually only used her for survival (eating) while their emotional attachment was exclusively to the cloth mother.
Permanence of Imprinting: Students often think imprinting is 100% permanent; however, later research (e.g., Guiton) suggested that imprinting effects can sometimes be reversed with social experience.
Species Confusion: Ensure you do not attribute the 'critical period' exclusively to one researcher; both utilized the concept, though Lorenz's window was much shorter than Harlow's.
