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Bases of Human Behaviour
Human behaviour is shaped by a complex interplay of biological, psychological, and cultural factors. This course explores the foundational concepts that explain why we think, feel, and act…
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A patient with damage to the hypothalamus is most likely to exhibit disturbances in which set of functions?
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If a stimulus is below the threshold for a neuron, which statement about the resulting nerve impulse is most accurate?
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During a fight‑or‑flight response, which endocrine gland releases hormones that directly stimulate the hypothalamus to prolong emotional arousal?
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A researcher compares two groups of children: one raised in a culture that emphasizes communal meals and another in a culture that emphasizes individual eating. Which process best accounts for the observed differences in eating habits?
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Which of the following best illustrates the difference between integration and assimilation as acculturative strategies?
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A mutation that creates a new allele for a gene involved in stress response is most likely to affect behaviour by:
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Which brain structure is primarily responsible for coordinating voluntary movements and storing motor memory patterns?
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A student argues that because the sympathetic division speeds up heart rate, it must be the only system controlling cardiovascular activity. Which concept best identifies the flaw in this reasoning?
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Which of the following statements about the all‑or‑none principle of nerve fibers is most accurate?
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In the dual inheritance theory, which of the following correctly pairs the transmission mode with its primary carrier?
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A child learns to greet elders by bowing after observing family members do so, without any explicit instruction. This learning exemplifies:
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Which statement best captures the relationship between the limbic system and the hypothalamus?
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A person with a lesion in the posterior pituitary would most likely experience deficits in:
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Which of the following best explains why the same stimulus can produce different behavioural responses in individuals from different cultures?
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During a reflex arc involving the knee‑jerk response, which part of the nervous system primarily mediates the action?
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Which of the following best describes the role of the thalamus in sensory processing?
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A researcher notes that a group of immigrants maintains their native language while adopting the host country's cuisine. This pattern most closely aligns with which acculturative strategy?
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Which of the following best illustrates the concept of “genetic preparedness” as described by Heidi Keller?
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A child raised in a community that values collective decision‑making is likely to develop which type of social cognition compared to a child from an individualistic culture?
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Which of the following best describes why the sympathetic and parasympathetic divisions are said to have opposite effects?
Understanding the Bases of Human Behaviour
Human behaviour is shaped by a complex interplay of biological, psychological, and cultural factors. This course explores the foundational concepts that explain why we think, feel, and act the way we do. By the end of the module, you will be able to describe key neuro‑biological mechanisms, explain the role of endocrine systems in stress responses, and differentiate between cultural processes such as enculturation, socialisation, integration, and assimilation.
1. Evolutionary Advantages of Brain Size
The human brain accounts for roughly 2.35% of total body weight. Although this may seem modest, it represents a remarkable evolutionary adaptation. The small proportion of body mass devoted to the brain reduces the metabolic cost of maintaining neural tissue while allowing a relatively large amount of cortical matter relative to body size. This high brain‑to‑body ratio supports complex cognition, abstract reasoning, and language—abilities that distinguish humans from most other species.
- Metabolic efficiency: A larger brain would demand more glucose and oxygen, increasing the energy burden on the organism.
- Neural density: Concentrating neural tissue in a compact organ enables faster signal transmission and more intricate neural networks.
- Behavioural flexibility: Enhanced cognitive capacity allows humans to adapt to diverse environments, a key factor in our species’ global success.
2. The Hypothalamus: A Master Regulator
The hypothalamus sits at the base of the brain and orchestrates essential homeostatic functions. Damage to this structure typically disrupts:
- Thermoregulation – the ability to maintain a stable internal temperature.
- Hunger and satiety – regulation of food intake through hormones such as ghrelin and leptin.
- Hormone secretion – control of the pituitary gland, which releases hormones that influence growth, reproduction, and stress responses.
Because the hypothalamus links the nervous system with the endocrine system, lesions often produce a cascade of physiological disturbances, highlighting its central role in maintaining internal equilibrium.
3. Neuronal Thresholds and Action Potentials
Neurons communicate via electrical impulses called action potentials. An action potential is only generated when a stimulus exceeds the neuron's threshold potential. If a stimulus is below this threshold, no nerve impulse is generated and the stimulus is not felt. This all‑or‑none principle ensures that signals are clear and reliable, preventing ambiguous or weak sensations from cluttering the nervous system.
Key points to remember:
- Thresholds are determined by the balance of sodium and potassium ions across the neuronal membrane.
- Once the threshold is reached, the amplitude of the action potential remains constant regardless of stimulus intensity.
- Sub‑threshold stimuli may still influence the neuron's excitability, but they do not produce a conscious perception.
4. The Fight‑or‑Flight Response and Endocrine Interaction
When faced with danger, the body initiates a rapid physiological response known as fight‑or‑flight. The adrenal medulla releases the catecholamines epinephrine (adrenaline) and norepinephrine. These hormones travel through the bloodstream and directly stimulate the hypothalamus, prolonging emotional arousal and preparing the organism for action.
Other endocrine glands, such as the pituitary, thyroid, and pancreas, play supportive but distinct roles. However, the adrenal medulla is the primary source of the immediate hormonal surge that amplifies the hypothalamic alert system.
5. Cultural Influences on Behaviour: Enculturation vs. Socialisation
Human behaviour is not solely dictated by biology; cultural contexts shape habits, values, and preferences. Consider two groups of children raised in different eating cultures—one emphasizing communal meals, the other promoting individual eating. The observed differences arise primarily through enculturation, the process by which individuals acquire the norms, values, and practices of their culture by observing and participating in everyday activities.
While socialisation involves explicit teaching (e.g., formal nutrition lessons), enculturation occurs implicitly through repeated exposure to culturally specific behaviours, such as shared dining rituals or solitary snack choices.
6. Acculturative Strategies: Integration vs. Assimilation
When individuals or groups encounter a new culture, they adopt various acculturative strategies. Integration refers to maintaining one's original cultural identity while also engaging with the host culture. In contrast, assimilation involves abandoning the original cultural identity in favour of the dominant culture.
Key distinctions include:
- Integration promotes bicultural competence, allowing individuals to navigate multiple cultural contexts.
- Assimilation often leads to loss of heritage language, traditions, and social networks.
- Both strategies influence psychological well‑being, but integration is generally associated with higher self‑esteem and lower stress levels.
7. Genetic Variation and Behavioural Evolution
Behavioural traits can be influenced by genetic mutations that create new alleles. A mutation affecting a gene involved in the stress response does not guarantee survival or directly increase intelligence. Instead, it provides raw material for natural selection. In changing environments, individuals carrying advantageous alleles may have higher reproductive success, gradually shaping the behavioural repertoire of a population.
This concept underscores the dynamic relationship between genetics and environment: genes set potentials, while cultural and ecological pressures determine which potentials are realised.
8. Motor Coordination and Memory: The Role of the Cerebellum
The cerebellum, located at the back of the brain beneath the occipital lobes, is essential for coordinating voluntary movements and storing motor memory patterns. It fine‑tunes motor commands, ensuring smooth, accurate, and timed actions. Damage to the cerebellum can result in ataxia—uncoordinated movements—and difficulty learning new motor skills.
Unlike the amygdala (emotion processing) or the hypothalamus (homeostasis), the cerebellum’s primary function is motoric, making it a critical hub for activities ranging from walking to playing a musical instrument.
9. Integrating Biological and Cultural Perspectives
To fully understand human behaviour, it is essential to adopt a biopsychosocial approach. Biological mechanisms—such as brain size, neuronal thresholds, and endocrine responses—provide the physiological foundation. Cultural processes—like enculturation, socialisation, integration, and assimilation—shape how these biological capacities are expressed in everyday life.
By recognising the interplay between innate predispositions and environmental influences, psychologists can develop more comprehensive models of behaviour, design effective interventions, and appreciate the diversity of human experience.
