Motivation and Hunger

1. Motivation

Motivation:
Needs or desires that energize and direct behavior toward a goal.

Examples of motives:

  • Food

  • Money

  • Love

  • Achievement

  • Safety

Motivation explains:

  • Why behavior begins

  • What direction behavior takes

  • How long behavior persists

2. Theories of Motivation

Instinct Theory

Instinct:
An innate (inborn) pattern of behavior shared by all members of a species.

Examples:

  • Babies sucking

  • Fear responses

  • Mate selection behaviors

Idea: Behavior is driven by genetically programmed instincts.

Drive Reduction Theory

Developed by Clark Hull

Drive Reduction Theory:
Physiological needs create a drive (state of tension) that motivates behavior to reduce the need and restore homeostasis.

Process:

Need → Drive → Behavior → Homeostasis restored

Example:

  • Heat → thirst → drink water → balance restored

Common drives:

  • Hunger

  • Thirst

  • Temperature regulation

Incentive Theory

Behavior is motivated by external stimuli (rewards or punishments).

Two forces:

Push: internal biological needs
Pull: external rewards or consequences

Examples:

  • Studying to earn good grades

  • Working for money

  • Avoiding danger

Types of Motivation

Intrinsic motivation

  • Doing something for internal satisfaction

  • Example: reading because you enjoy learning

Extrinsic motivation

  • Doing something for external reward or to avoid punishment

  • Example: studying for money or grades

Overjustification Effect

When external rewards reduce intrinsic motivation.

Example:
A child who loves drawing begins drawing only for rewards.

Arousal Theory

People seek an optimal level of arousal (alertness or excitement).

Some people seek:

  • Thrill

  • Adventure

  • Novel experiences

Example:

  • Skydiving

  • Roller coasters

Yerkes–Dodson Law

Performance increases with moderate arousal, but too little or too much reduces performance.

Relationship forms an inverted U-shaped curve.

Maslow's Hierarchy of Needs

Developed by Abraham Maslow

Humans are motivated to satisfy needs in a hierarchical order.

Levels

  1. Physiological needs

    • Food

    • Water

    • Sex

    • Sleep

  2. Safety needs

    • Shelter

    • Security

    • Protection

  3. Love and belonging

    • Friendship

    • Family

    • Social acceptance

  4. Esteem

    • Self-respect

    • Recognition

    • Achievement

  5. Self-actualization

    • Reaching full potential

    • Personal growth

    • Creativity

Criticism:
Some people achieve higher needs even when lower needs are not fully met.

3. Achievement Motivation

Studied by David McClelland

Achievement motivation:
Desire to accomplish goals and meet standards of excellence.

Two factors:

  • Desire for success

  • Fear of failure

People high in achievement motivation:

  • Choose moderately difficult tasks

People with high fear of failure:

  • Choose very easy tasks

  • Or impossibly difficult tasks

4. Types of Conflict (Motivation Conflicts)

Approach–Approach Conflict

Choice between two positive options.

Example:
Choosing between two colleges.

Avoidance–Avoidance Conflict

Choice between two negative options.

Example:
Do homework or do chores.

Approach–Avoidance Conflict

One choice with both positive and negative aspects.

Example:
Eating cake (tastes good but high calories).

Multiple Approach–Avoidance Conflict

Two choices that each have pros and cons.

Example:
Expensive sports car vs. affordable practical car.

5. Hunger Motivation

Hunger is influenced by biological and psychological factors.

Hypothalamus and Hunger

Two important brain areas:

Lateral Hypothalamus

Triggers hunger.

Ventromedial Hypothalamus

Controls satiety (feeling full).

Blood Chemistry and Hunger

Two key substances:

Glucose

Sugar in the blood used for energy.

Insulin

Hormone that allows cells to absorb glucose.

Low glucose → hunger signal
High glucose → feeling full

Organs Involved

Pancreas

  • Releases insulin

  • Maintains blood glucose balance

Liver

  • Stores glucose as glycogen

  • Releases glucose when needed

Glucoreceptors

Located in:

  • Hypothalamus

  • Liver

They detect blood glucose levels.

Low glucose → hunger
High glucose → satiety

6. Psychological Influences on Eating

Short-Term Cues

Immediate factors influencing eating:

  • Taste

  • Smell

  • Texture

  • Temperature

  • Food preference

These cues can override physiological hunger.

Long-Term Cues (Set Point Theory)

Set Point Theory:
Body tries to maintain a stable weight level.

Hormone involved:

Leptin

  • Regulates fat storage

  • Influences metabolism

If weight drops:

  • Metabolism slows

If weight increases:

  • Metabolism speeds up

This explains yo-yo dieting.

7. Eating Disorders

Obesity

Excess body fat linked to:

  • Diabetes

  • Heart disease

  • Other health problems

Anorexia Nervosa

  • Self-starvation

  • Extreme weight loss

  • Fear of gaining weight

Bulimia Nervosa

Cycle of:

  • Binge eating

  • Purging (vomiting or laxatives)

Both disorders can lead to serious medical consequences or death.