BIOLOGICAL BASES

• Motivation is defined as a need or desire that serves to energize or direct behavior.

• Evolutionary theory states that animals are motivated to act by basic needs critical to the survival of the organism.

• Hunger, thirst, sleep, and reproduction needs are primary drives.

• The desire to obtain learned reinforcers, such as money or social acceptance, is a secondary drive.

• The interaction between the brain and motivation was noticed when Olds and Milner discovered that rats would press a bar in order to send a small electrical pulse into certain areas of their brains.

  • This phenomenon is known as intracranial self-stimulation.

• Instinct theory, supported by evolutionary psychology, posits that the learning of species-specific behavior motivates organisms to do what is necessary to ensure their survival.

• Arousal theory states that the main reason people are motivated to perform any action is to maintain an ideal level of physiological arousal.

  • Arousal is a direct correlate of nervous system activity.

• The Yerkes-Dodson law states that tasks of moderate difficulty, neither too easy nor too hard, elicit the highest level of performance.

• The opponent process theory is a theory of motivation that is clearly relevant to the concept of addiction.

• The drive-reduction theory of motivation posits that psychological needs put stress on the body and that we are motivated to reduce this negative experience.

• Homeostasis is a state of regulatory equilibrium.

• When our nutrient supply is replenished, a signal is issued to stop eating.

• The common analogy for this process is a home thermostat in a heating-cooling system.

  • It has a target temperature, called the set point.

• The job of the thermostat is to maintain the set point.

  • If body weight rises above the set point, the action of the ventromedial hypothalamus will send messages to the brain to eat less and to exercise more.

  • When body weight falls below the set point, the brain sends messages to eat more and exercise less through the lateral hypothalamus.

HUNGER, THIRST, AND SEX

• The homeostatic regulation model provides a biological explanation for the efficacy of primary reinforcers such as hunger and sex.

  • The brain provides a large amount of control over feeding behavior.

  • Specifically, the hypothalamus has been identified as an area controlling feeding.

    • The hypothalamus is a small part of the brain located just beneath the thalamus.

• Leptin plays a role in the feedback loop between signals from the hypothalamus and those from the stomach.

  • Leptin is released in response to a buildup of fat cells when enough energy has been consumed.

• The feedback loop that controls eating can be broken by damaging the hypothalamus, but the operation of this mechanism raises the question of what is actually monitored and regulated in normal feeding behavior.

  • Two prime candidates exist.

    • The first candidate hypothesis is blood glucose.

    • This idea forms the basis for the glucostatic hypothesis.

  • Glucose is the primary fuel of the brain and most other organs.

  • When insulin (a hormone produced by the pancreas to regulate glucose) rises, glucose decreases.

• A second candidate hypothesis is called the lipostatic hypothesis.

  • As you might have guessed, this theory states that fat is the measured and controlled substance in the body that regulates hunger.

• There are several disorders related to eating habits, body weight, and body image that have their roots in psychological causes.

  • Anorexia nervosa, which is more prevalent in females, is an eating disorder characterized by an individual being 15 percent below ideal body weight.

  • Body dysmorphia, or a distorted body image, is key to understanding this disorder.

  • Another related eating disorder is bulimia nervosa, which is characterized by alternating periods of binging and purging.

• Like the motivations to eat and drink, the motivation to reproduce relies on the hypothalamus, which stimulates the pituitary gland and ultimately the production of androgens and estrogens.

  • Androgens and estrogens are the primary sexual hormones in males and females, respectively.

THEORIES OF MOTIVATION

Biological Theory

• As discussed in the “biological bases” of motivation, early theories on motivation relied on a purely biological explanation of motivated behavior.

• Animals, especially less complex animals, are thought to be motivated by instinct, genetically programmed patterns of behavior.

Humanistic Theory

• Abraham Maslow proposed a hierarchical system for organizing needs.

  • This hierarchy can be divided into five levels.

  • Each lower-level need must be met in order for an attempt to be made to fill the next category of needs in the hierarchy.

• Self-actualization occurs when people creatively and meaningfully fulfill their own potential.

  • This is the ultimate goal of human beings according to Maslow’s theory.

Cognitive Theories

• Cognitive psychologists divide the factors that motivate behavior into intrinsic and extrinsic factors: that is, factors originating from within ourselves and factors coming from the outside world, respectively

• Extrinsic motivators are often associated with the pressures of society, such as getting an education, having a job, and being sociable.

• Intrinsic motivators, in contrast, are associated with creativity and enjoyment.

  • Over time, our intrinsic motivation may decrease if we receive extrinsic rewards for the same behavior.

    • This phenomenon is called the overjustification effect.

  • An important intrinsic motivator is the need for self-determination, or the need to feel competent and in control.

• Related to the concept of self-determination is self-efficacy, or the belief that we can or cannot attain a particular goal.

• Also closely related to this is achievement motivation, the need to reach realistic goals that wintrinsic motivatore set for ourselves.

• Henry Murray believed that, although motivation is rooted in biology, individual differences and varying environments can cause motivations and needs to be expressed in many different ways.

Social Theory

• Another cognitive theory of motivation concerns the need to avoid cognitive dissonance.

• Kurt Lewin classified conflicts into four types.

• In an approach-approach conflict, one has to decide between two desirable options, such as having to choose between two colleges of similar characteristics.

• Avoidance-avoidance is a similar dilemma.

  • Here, one has to choose between two unpleasant alternatives.

• In approach-avoidance conflicts, only one choice is presented, but it carries both pluses and minuses.

THEORIES OF EMOTION

• Emotions are experiential and subjective responses to certain internal and external stimuli.

• Emotion consists of three components: a physiological (body) component, a behavioral (action) component, and a cognitive (mind) component.

  • The physical aspect of emotion is one of physiological arousal, or an excitation of the body’s internal state.

  • The behavioral aspect of emotion includes some kind of expressive behavior.

  • The cognitive aspect of emotion involves an appraisal or interpretation of the situation.

• James-Lange theory posits that environmental stimuli cause physiological changes and responses.

• The Cannon-Bard theory arose as a response to the James-Lange theory.

  • The Cannon-Bard theory asserts that the physiological response to an emotion and the experience of emotion occur simultaneously in response to an emotion-provoking stimulus.

• The two-factor theory, proposed by Schachter and Singer, adds a cognitive twist to the James-Lange theory.

  • The first factor is physiological arousal; the second factor is the way in which we cognitively label the experience of arousal.

• A scientist and pioneer in the study of emotions, Paul Ekman observed facial expressions from a variety of cultures and pointed out that, regardless of where two persons were from, their expressions of certain emotions were almost identical.

• Darwin’s ideas also led to the facial feedback hypothesis, the idea that a person’s facial expression can influence the actual emotion being experienced.

THE ROLE OF THE LIMBIC SYSTEM IN EMOTION

• The limbic system is a collection of brain structures that lie on both sides of the thalamus; together, these structures appear to be primarily responsible for emotional experiences.

• The amygdala plays an especially key role in the identification and expression of fear and aggression.

Emotion, Memory, Decision-Making, and the Autonomic Nervous System

• Emotional experiences can be stored as memories that can be recalled by similar circumstances.

  • The limbic system also includes the hippocampus, a brain structure that plays a key role in forming memories.

• Similar circumstances to a traumatic event can lead to recall of the memory of the experience, referred to as flashback.

• The prefrontal cortex is critical for emotional experience, and it is also important in temperament and decision-making.

  • It is associated with a reduction in emotional feelings, especially fear and anxiety, and is often activated by methods of emotion regulation and stress relief.

• The autonomic nervous system (ANS) is responsible for controlling the activities of most of the organs and glands, and it controls arousal.

• The sympathetic nervous system (SNS) provides the body with brief, intense, vigorous responses.

• The parasympathetic nervous system (PNS) provides signals to the internal organs during a calm resting state when no crisis is present.

• An increase in these physiological functions is associated with the sympathetic response, or fight-or-flight response.

STRESS

• Stress causes a person to feel challenged or endangered.

  • Although this definition may make you think of experiences such as being attacked, in reality, most stressors (events that cause stress) are everyday events or situations that challenge us in more subtle ways.

    • Some stressors are transient, meaning that they are temporary challenges.

• The physiological response to stress is related to the fight-or-flight response, a concept developed by Walter Cannon and enhanced by Hans Selye into the general adaptation syndrome.

• Alarm refers to the arousal of the sympathetic nervous system, resulting in the release of various stimulatory hormones, including corticosterone, which is used as a physiological index of stress.

• Resistance is the result of parasympathetic rebound.

• If the stressor persists for long periods of time, the stress response continues into the exhaustion phase.

• Richard Lazarus developed a cognitive theory of how we respond to stress.

• The Type-A pattern of behavior is typified by competitiveness, a sense of time urgency, and elevated feelings of anger and hostility.

• The Type-B pattern of behavior is characterized by a low level of competitiveness, low preoccupation with time issues, and a generally easygoing attitude.

Next Chapter: Chapter 15: Personality