Motivation and Emotion: Biological, Psychological, and Social Perspectives

Motivation

Definition and Characteristics

Motivation is a fundamental psychological process that arouses, directs, and maintains behaviour. It is not directly observable but is inferred from actions and is used to explain fluctuations in behaviour over time.

• Definition: Psychological process that arouses, directs, and maintains behaviour.

• Inferred Process: Motivation is deduced from observed behaviour, not directly measured.

• Behavioural Fluctuations: Explains why behaviour changes over time.

Instinct Theory: Historical Perspectives

Early theories of motivation focused on instincts as inherited patterns of behaviour.

• Darwin: Introduced the concept of instincts as complex, inherited behaviour patterns typical of a species.

• Watson: Rejected instincts, arguing they were endless and could not adequately explain behaviour, thus maintaining the status quo.

Drive Reduction Theory (Clark Hull)

Drive reduction theory explains motivation as a process of reducing physiological needs and restoring homeostasis.

• Need: Caused by physiological deprivation (e.g., hunger, thirst).

• Drive: State of tension induced by a need.

• Behaviour: Actions taken to reduce tension and satisfy the need.

• Homeostasis: Steady state of physiological equilibrium.

Example: Thermostat Analogy

A thermostat regulates air temperature by detecting deviations from a set point and activating a correctional mechanism (electric heater) via negative feedback.

• Set Point: Desired value (e.g., temperature or body weight).

• Negative Feedback: Mechanism that restores equilibrium.

Hunger Motivation

Factors Regulating Hunger

Hunger is regulated by multiple physiological and social factors.

• Taste Receptors: Detect food and influence desire to eat.

• Liver: Monitors blood glucose levels.

• External Factors: Availability and attractiveness of food.

• Social Factors: Cultural norms and social eating.

• Stomach: Signals fullness or emptiness.

Role of the Hypothalamus in Hunger Regulation

The hypothalamus is a key brain region involved in hunger regulation.

• Lateral Hypothalamus: Acts as an accelerator pedal; stimulation causes hunger, damage leads to starvation.

• Ventromedial Hypothalamus: Acts as a brake pedal; stimulation causes satiety, damage leads to overeating and obesity.

Obesity and Set Point Theory

Prevalence and Trends

• 31% of Americans are overweight (compared to 25% in 1950).

• 42% are obese (doubled over a century).

• Obesity is defined as being 20% greater than ideal for height/build.

• 73% are overweight or obese.

Set Point Theory

The set point theory suggests that body weight is regulated by a biological 'thermostat' that controls fat storage and hunger.

• Fat Cells: Grow in size and number; losing weight reduces size but not number.

• Dieting: Can induce constant hunger and increase set point (yo-yo effect).

Basal Metabolic Rate (BMR)

• BMR: Rate at which the body burns calories.

• Defending Set Point: Body alters BMR to maintain set point, influenced by genetics and early diet.

Genetic and Environmental Contributions

Both genetic and environmental factors influence obesity.

• Genetic: Risk increases if one or both parents are obese.

• Environmental: Early eating habits affect adult obesity; parental monitoring is advised.

Table: Genetic Contribution to Obesity

# Obese Parents	Obese as Adult (%)
0	~10%
1	~40%
2	~80%

Table: Role of Environment in Obesity

Child's Age	Obese as Adult (%)
Infant	Low (Not Obese), Moderate (Obese)
7 yrs	Low (Not Obese), Higher (Obese)
10-13 yrs	Low (Not Obese), Highest (Obese)

Eating Disorders

Anorexia Nervosa

Anorexia nervosa is a life-threatening disorder characterized by severe restriction of calorie intake and distorted body image.

• 85% of cases are women; 25% relapse rate; 5% mortality rate.

• Prevalence: 3/1000 young women in grades 9-12.

• Symptoms: Amenorrhea, dry/cracking skin, constipation, increased heart rate, lanugo (fine hair), immature features.

Theories of Anorexia Nervosa

• Freudian: Eating substitutes for sex.

• Family: Struggle for independence.

• Biological: Genetic factors, damaged hypothalamus.

• Learning: Influence of society's ideal body image.

Bulimia Nervosa

Bulimia nervosa involves cycles of binge eating followed by purging (vomiting or laxative abuse).

• 90% of cases are women; 1-2% of college women.

• Typically affects white women in early 20s.

• Often normal weight but with distorted body image.

• Family history of obesity and alcoholism is common.

Psychological and Physiological Effects

Psychological	Physiological
Depression	Swollen salivary glands
Hours binging and purging	Broken vessels in eye
Restricted social capacity	Sore throat, eroded tooth enamel
Work problems	Dehydration, intestinal damage, nutrition deficits, potassium imbalance

Emotion

Definition

Emotion is a motivated state marked by physiological arousal, expressive behaviour, and mental experience, varying in intensity and pleasantness.

Expression of Emotions

• Facial expressions promote survival.

• Evidence: Quick identification of frowns, facial expressions in deaf/blind individuals, universality across cultures.

Physiological Theories of Emotion

James-Lange Theory

• Emotion follows physiological changes or chemistry.

• Emotion is a consequence of physiology (e.g., we feel sorry because we cry).

• Supported by dramatic actors.

Cannon's Critique

• People poorly perceive subtle physiological changes.

• Different emotions can be associated with the same arousal.

• Physiological changes depend on slow-moving hormones, which cannot account for rapid emotional responses.

Neural Pathways of Emotion

• Thalamus enables instant fear response via shortcut to amygdala.

• Visual cortex provides slower, interpretive response.

Behavioural Theories: Facial Feedback

• Facial expressions can influence emotional experience ("put on a happy face").

• Blood flow and muscle tension provide sensory feedback to the brain, evoking unique emotional responses.

Cognitive Theories: Schachter/Singer Two-Factor Theory

• Emotions depend on subjective interpretation (attribution) of situations.

• Emotion is the product of two factors: physiological arousal and an attributed cause.

Example: Dutton & Aron (1978) "Love on the Bridge"

Bridge	Fear Level	Height
Swinging Bridge	High	450 feet above fast water
Sturdy Bridge	Low	10 feet above stream

Single males greeted by experimenter, asked to write a story and given experimenter's phone number. High fear increased likelihood of contacting experimenter, supporting the two-factor theory.

Critique of Two-Factor Theory

• Emotions can occur without arousal.

• Different emotions have distinct physiological correlates.

• Effect is difficult to replicate.

Additional info:

• Set point theory and BMR are important in understanding obesity and dieting.

• Eating disorders have multifactorial etiologies, including psychological, biological, and social factors.

• Emotion theories highlight the interplay between physiological, behavioural, and cognitive processes.