The Bases of Human Behaviour Class 11 Psychology

Evolutionary Perspective

• Each person exhibits unique physical and psychological traits resulting from the interplay between their genetic makeup and environmental factors.
• Biologists hold the belief that species have undergone an evolutionary process from their original forms to their present state.
• Evolution is a gradual and systematic biological transformation of a species from its previous state, brought about by the changing adaptive requirements of its environment.
• Evolution is driven by the mechanism of "Natural Selection".

Important features of 'modern human beings':

• Developed Brain (with increased capacity for cognition and behaviour)
• Developed ability of walking (can walk upright on two legs)
• A free hand (with a workable opposing thumb

Biological and Cultural Roots

• Along with a shared biological system, human beings also share certain cultural systems.
• Culture exposes us to diverse experiences and learning opportunities by placing us in a variety of situations. These experiences, opportunities, and demands exert a significant influence on our behavior.
• Therefore, in addition to a biological basis, there is also a cultural basis for human behavior.

Biological Basis of Behaviour

Neurons

• Neurons are the building blocks of the nervous system. They are specialized cells that can convert various types of stimuli into electrical impulses. They are also specialized for receiving, conducting, and transmitting information in the form of electrochemical signals.
• Neurons receive information from sensory organs or from other adjacent neurons and carry this information to the central nervous system. They also carry motor information from the central nervous system to motor organs.
• Neurons come in many different types, which can vary greatly in terms of their shape, size, chemical composition, and function. 

Despite these differences, all neurons share three fundamental components: the soma, dendrites, and axon.

• Soma- It is also known as the cell body, contains the nucleus which stores the genetic material of the neuron. The Soma also houses most of the cytoplasm of the neuron.
• Dendrites- It serve as the receiving ends of neurons. They receive neural impulses from several adjacent neurons or directly from the sense organs.

• Axon- The longer single branched extension. Received information is passed to axon so that the information is relayed to another neuron or to muscles.
• Terminal buttons- They are the terminal points of axon. These buttons transmits the information to another neuron, gland and muscle.
  

Nerve impulse

Electrical signals called nerve impulses are used to transmit information within the nervous system. Neurons follow the "all or none principle," which means that they either respond fully or not at all.

Synapse 

The junction between two neurons is called a synapse, and there is a small gap called the synaptic cleft between them. The transmission of neural impulses from one neuron to another occurs through a complex process called synaptic transmission.

Structure and Functions of Nervous System and Endocrine System and Their Relationship with Behaviour and Experience

The nervous system and endocrine system are crucial in shaping human behavior and experience.

Nervous System

• The human nervous system is the most complex and developed among living creatures.
• It can be divided into the Central Nervous System (CNS) and Peripheral Nervous System (PNS).
• The CNS includes the brain and spinal cord, located inside the cranium and backbone.
• The PNS, outside the bony cases, is further classified into Somatic and Autonomic nervous systems.
• The Somatic system controls voluntary actions, while the Autonomic system regulates involuntary functions.

The Peripheral Nervous System

• The PNS comprises all neurons and nerve fibers linking the CNS to the body.
• It is split into the Somatic Nervous System and Autonomic Nervous System.
• The Autonomic Nervous System has two further divisions: Sympathetic and Parasympathetic systems.
• The PNS transmits information from sensory receptors to the CNS and relays motor commands from the brain to muscles and glands.

The Somatic Nervous System

• Comprises cranial nerves and spinal nerves.
• There are twelve sets of cranial nerves, including sensory, motor, and mixed types.
• Cranial nerves gather sensory data from head receptors and convey them to the brain.
• Motor cranial nerves transmit motor impulses from the brain to head muscles.
• Spinal nerves (31 sets) have sensory and motor functions, collecting sensory data from the body (except the head) and sending it to the spinal cord.

The Autonomic Nervous System

• Regulates involuntary body functions like breathing, circulation, and digestion.
• Comprises the Sympathetic and Parasympathetic divisions.
• Sympathetic division activates during emergencies, redirecting blood flow to muscles and increasing vital functions.
• Parasympathetic division conserves energy, regulating routine bodily functions and returning the body to a calm state post-emergency.

The Central Nervous System

• The central nervous system (CNS) serves as the hub of all neural activity.
• It consolidates incoming sensory data, conducts various cognitive functions, and issues motor commands to muscles and glands.
• The CNS consists of:
  1. The brain
  2. The spinal cord

The Brain and Behavior

• The human brain is thought to have evolved over millions of years from lower animal brains, with this evolutionary process ongoing.
• Brain structures can be categorized into different levels based on their evolutionary timeline.
• Key brain structures:
  • The limbic system, brain stem, and cerebellum are among the oldest structures.
  • The Cerebral Cortex represents the latest development in brain evolution.
• An adult brain typically weighs about 1.36 kg and houses approximately 100 billion neurons.
• Although the brain's neuron count is impressive, its true wonder lies in its capacity to influence human behavior and cognition.
• The brain is segmented into specialized structures and regions, each carrying out distinct functions.
• Brain scans demonstrate that while some mental functions are spread across various brain regions, many functions are localized as well.
• For instance, the occipital lobe is specialized for processing vision.

Structure of the Brain

The brain can be classified into three main parts for study purposes: Hindbrain, Midbrain, and Forebrain.

Hindbrain

• Medulla Oblongata: The lowest part of the brain, connected to the spinal cord, controlling vital functions like breathing, heart rate, and blood pressure. It also oversees autonomic activities.
• Pons: Links medulla to the midbrain, involved in processing auditory signals and potentially associated with dreaming during sleep. It influences breathing, facial expressions, and other motor functions.
• Cerebellum: Recognizable by its folded appearance, it maintains posture, balance, and coordinates muscle movements. It assists in the execution of motor commands from the forebrain and stores movement patterns in memory.

Midbrain

• The midbrain, connecting the hindbrain to the forebrain, contains neural centers responsible for specific reflexes, and processes visual and auditory stimuli. The Reticular Activating System (RAS) within the midbrain regulates arousal levels, alertness, and selective attention to sensory inputs.

Forebrain

• Hypothalamus: Despite its small size, it crucially influences emotional and motivational behaviors like eating, drinking, and sleeping. It regulates physiological processes, internal body environment, and hormone secretion.
• Thalamus: Acts as a relay station for sensory inputs from sense organs to the cortex for processing. It also relays motor signals from the cortex to the appropriate body parts for action.
• The Limbic System: Comprises structures in the old mammalian brain. Regulates internal homeostasis by controlling body temperature, blood pressure, and blood sugar levels. Key components include the hypothalamus, Hippocampus, and Amygdala. The Hippocampus is vital for long-term memory, while the Amygdala influences emotional behavior.
  
• The Cerebrum (Cerebral Cortex): Manages higher cognitive functions like attention, perception, learning, memory, language, reasoning, and problem-solving. Comprises two-thirds of the brain's mass, with varying thickness covering the brain's surface. Divided into two symmetrical Cerebral Hemispheres, each with specialized functions. Connected by the Corpus Callosum, allowing communication between the hemispheres. Further divided into four lobes - Frontal, Parietal, Temporal, and Occipital - each with distinct functions.

Brain Functions and Localisation:

• No single brain part exclusively performs a task, but certain functions are localized in specific cortex areas.
• For instance, driving involves visual processing in the Occipital lobe, auditory processing in the Temporal lobe, motor control in the Parietal lobe, and decision-making in the Frontal lobe.
• The brain functions as a coordinated unit where different parts contribute distinct roles.

Spinal Cord

• The spinal cord is a long bundle of nerve fibers that extends along the entire length within the spine.
• One end of the spinal cord is connected to the brain's medulla, while the other end is free at the tail end.
• Throughout its length, the structure of the spinal cord remains consistent.
• The central part of the spinal cord contains a butterfly-shaped mass of grey matter housing association neurons and other cells.
• Surrounding the grey matter is the white matter of the spinal cord, comprised of ascending and descending neural tracts.
• These neural tracts serve to connect the brain to the rest of the body, functioning as pathways for nerve fibers.
• The spinal cord acts as a major communication cable, facilitating the exchange of numerous messages with the central nervous system (CNS).
• It serves two primary functions: transmitting sensory impulses from the lower body parts to the brain and conveying motor impulses from the brain to various parts of the body.
• Additionally, the spinal cord performs basic reflex actions that do not require brain involvement.
• Simple reflexes involve a sensory nerve, a motor nerve, and the association neurons found in the grey matter of the spinal cord.

Reflex Action

• A reflex is an involuntary and rapid action triggered by specific stimuli, occurring automatically without conscious brain intervention.
• Reflex actions are ingrained in our nervous system through evolutionary processes, such as the instinctive eye-blinking reflex.
• Common reflex actions include the knee-jerk response, pupil constriction, withdrawal from extreme temperatures, breathing, and stretching.
• These reflex actions are primarily governed by the spinal cord and do not necessitate brain processing.
• They serve to protect the organism from potential threats and ensure survival.

The Endocrine System

• The endocrine glands are essential for development and behavior, secreting hormones that influence behaviors. These glands, also known as ductless or endocrine glands, release hormones directly into the bloodstream as they lack ducts.
• The endocrine system, consisting of these glands, collaborates with the nervous system, forming the neuroendocrine system.
• Major endocrine glands include the pituitary gland.

Pituitary Gland

• Situated below the hypothalamus in the cranium, the pituitary gland comprises the anterior and posterior pituitary.
• The anterior pituitary interacts with the hypothalamus, controlling its hormone secretions. Releasing various hormones, including growth hormone, it regulates other endocrine glands, earning the title of "master gland."
• Hormones are secreted either continuously or at specific life stages, such as puberty, triggering primary and secondary sexual changes.

Thyroid Gland

• Located in the neck, the thyroid gland produces thyroxin, impacting the body's metabolic rate.
• Thyroxin secretion is regulated by Thyroid Stimulating Hormone from the anterior pituitary, influencing energy production, oxygen consumption, and waste elimination in cells.
• Inadequate thyroxin leads to physical and mental sluggishness, while removal of the thyroid gland in young animals results in growth retardation and sexual development issues.

Adrenal Gland

• The adrenal gland is situated above each kidney and comprises two parts: the adrenal cortex and adrenal medulla, both responsible for secreting distinct hormones.
• Control and regulation of adrenal cortex secretion are orchestrated by Adrenocorticotrophic Hormone (ACTH) from the anterior pituitary gland. Decreased adrenal cortex secretion prompts the anterior pituitary to boost ACTH secretion, stimulating the adrenal cortex for increased hormone production.
• The adrenal cortex produces corticoids vital for various physiological functions, such as regulating body minerals like sodium, potassium, and chlorides. Any dysfunction in its operation significantly impacts nervous system functions.
• The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline). These hormones induce sympathetic activation leading to increased heart rate, oxygen consumption, metabolic rate, muscle tone, etc. Epinephrine and norepinephrine also trigger the hypothalamus, prolonging emotional responses even after the stressor's removal.

Pancreas

• Located near the stomach, the pancreas aids in food digestion and produces insulin. Insulin facilitates the breakdown of glucose by the liver for body use or storage as glycogen. Inadequate insulin secretion results in diabetes mellitus.

Gonads

• Gonads are the testes in males and ovaries in females, responsible for regulating sexual behaviors and reproductive functions through hormone secretion.
• Secretion of gonadal hormones is initiated by gonadotrophic hormone (GTH) from the anterior pituitary at puberty, stimulating hormone release that influences primary and secondary sexual characteristics.
• In females, the ovaries produce estrogens and progesterone. Estrogens drive female sexual development, affecting reproductive processes and secondary sexual characteristics. Progesterone prepares the uterus for potential ovum implantation.
• In males, the testes produce sperm continuously and secrete androgens, primarily testosterone. Testosterone triggers secondary sexual changes, behavioral shifts, and physical developments.

Heredity: Genes and Behavior

• We receive characteristics from our parents through genes, creating a unique genetic blueprint at birth.
• Genetics is the study of inheriting physical and psychological traits from ancestors.
• A zygote, formed from the fusion of the mother's ovum and the father's sperm, contains chromosomes inherited from each parent.

Chromosomes

• Chromosomes are threadlike structures in the cell nucleus, carrying genes and are constant for each organism.
• Humans inherit 46 chromosomes (23 from each parent) at conception, determining genetic traits.
• The 23rd chromosome from the father determines the child's sex (XX for female, XY for male).
• Chromosomes are mainly composed of DNA, which holds genes controlling traits at specific locations.

Genes

• Genes, stored in chromosomes, influence an organism's development by producing proteins.
• Genes determine an organism's phenotype (observable traits) and genotype (traits passed to offspring).
• Mutations, changes in genes, generate genetic variation allowing species evolution.
• Mutations lead to new gene combinations, tested by the environment for suitability.

Cultural Basis: Socio-Cultural Shaping of Behaviour

• Human behavior is influenced by hormones and reflexes, but these factors alone do not explain all behaviors.
• Culture plays a significant role in regulating human behavior, making it more complex than animal behavior.
• Examples like food preferences and sexual behavior demonstrate the complexity of human behavior influenced by culture.
• Human behavior is shaped by an interplay of biological and cultural forces, making humans similar in some ways and different in others.

Concept of Culture

• Human behavior is fundamentally social and cultural, involving interactions with others and engagement with cultural products.
• Culture refers to the man-made part of the environment, including material objects, ideas, and social institutions that influence behavior.
• Culture shapes behavior significantly, but individuals also contribute to shaping culture through interactive processes.
• Definitions of culture highlight its role in providing meaning, creating significant categories, and influencing human behavior.

Cultural Transmission

• Humans are both biological and socio-cultural beings, fulfilling vital needs and benefiting from acquired skills and experiences.
• Enculturation and socialization processes make humans cultural beings, displaying unique forms of behavior created by culture.
• Education and learning play a crucial role in human development, distinguishing humans with their capacity for learning and cultural creations.

Enculturation

• Enculturation is the process of learning that occurs without direct teaching, where individuals absorb ideas, concepts, and values from their cultural environment.
• Examples such as distinguishing between what is considered a "vegetable" or a "weed" are based on cultural norms and agreements within a community.
• The transmission of such concepts happens both directly and indirectly and is ingrained in the life of a cultural group without being questioned, known as enculturation.
• Enculturation encompasses all learning that happens due to the influence of one's socio-cultural surroundings, with a key aspect being learning through observation.
• Many behaviors and practices, like cooking in Indian families, are acquired through observation and participation rather than formal instruction, showcasing the impact of enculturation.
• Despite its pervasive effects, individuals often remain unaware of how deeply enculturation shapes their beliefs and behaviors, leading to a lack of conscious recognition of their culture's influence.
• Individuals who are highly enculturated may paradoxically be the least cognizant of the extent to which their cultural background molds their perceptions and actions.

Socialisation

• Socialisation is the process through which individuals acquire knowledge, skills, and behaviors to effectively participate in groups and society throughout their lives.
• It involves learning and developing ways to function effectively at any developmental stage and is crucial for the transmission of social and cultural values across generations.
• Failure in socialisation can pose a threat to the existence of a society.
• Humans have the capacity for a wide range of behaviors, but they typically exhibit behaviors learned within their social contexts, such as language acquisition and emotional expression norms.

Socialisation Agents

• Socialisation agents, including parents, teachers, and elders, play a significant role in shaping individuals' behaviors through teaching, reward, and punishment.
• Socialisation is not a one-way process; individuals not only receive influence from their social environments but also have an impact on them.
• Enculturation and socialisation lead to behavioral similarities within societies and differences across societies, with socialisation involving deliberate teaching and enculturation occurring without explicit instruction.
• Language learning is an example of both enculturation and socialisation, with some aspects learned spontaneously and others through direct teaching.
• Parents are crucial socialisation agents who influence children's development through various strategies, such as rewarding desired behaviors and providing diverse experiences.
• Schools play a significant role in socialisation by imparting cognitive and social skills, reinforcing societal norms, and fostering qualities like self-initiative and responsibility.
• Peer groups in middle childhood are important for socialization, promoting qualities like sharing, trust, and self-identity development through interactions and collective activities.
• The media has become a notable socialization agent, influencing individuals' behaviors and perceptions through television, cinema, and other mediums, with concerns about the impact of media violence on behavior.

Acculturation

• Refers to cultural and psychological changes resulting from contact with other cultures, which can be direct or indirect, voluntary or involuntary.
• People often need to learn new things to negotiate life with individuals from different cultural groups.
• Acculturation can occur at any stage of life, requiring re-learning of norms, values, and behaviors.
• Psychological changes during acculturation have been widely studied, often involving conflict and the need for resolution strategies.
• Acculturation can lead to both smooth transitions and difficulties in adapting to new cultural demands.

Acculturation Strategies:

• Integration: Involves maintaining one's original culture and identity while engaging in interactions with other cultural groups.
• Assimilation: Involves losing one's cultural identity to become part of another culture.
• Separation: Involves valuing one's original culture and avoiding interactions with other cultural groups.
• Marginalization: Involves little interest in cultural maintenance and relations with other cultural groups, leading to stress and indecision.