Recap - Motivational Systems
Human Motivation and
Emotion
{
Two systems
z
z
46-332-01
Dr. Fuschia Sirois
Lecture 4 Sept. 19, 2006
{
{
1) aversive motivation - BIS
2) appetitive motivation – BAS
Greater BIS sensitivity should be
reflected in greater proneness to anxiety
Greater BAS sensitivity causes the
person to begin (or to increase)
movement toward goals
Gray’s Three-Arousal Model
Reward Cues
Needs & Drives
Punishment Cues
+
Behavioural Activation
System (BAS)
-
+
Behavioural Inhibition
System (BIS)
+
+
Any condition necessary for life, growth
and well-being
All needs generate energy – motivation to
satisfy that need
Distinctions are based on
{
{
Nonspecific Arousal
System (NAS)
{
z
z
+
Decision
Mechanism
+
Approach / Active
avoidance
Deficiency vs. growth motivation
Directional effects, i.e., attention and action
Biological needs
+
+
– deficient biological condition
Psychological drives
z
Stop / Inspect
Conscious manifestation of an underlying
biological need
1
Primary motives: biological needs
Drives
{
Drive-Reduction
z
{
Physiological need creates an aroused
tension state (a drive) that motivates
us to satisfy the need
Need
(e.g., for
food, water)
Drive
(hunger, thirst)
Homeostasis: biological
“thermostats”
z
Drive-reducing
behaviors
(eating, drinking)
z
homeostasis is a process by which
internal body mechanisms sense
biological imbalances and stimulate
action to restore the proper balances
homeostatic controls exist for hunger,
thirst, body temperature, electrolyte
levels, etc.
Rest
Physiological Needs
Physiological Needs
Homeostasis
Negative feedback
{
Multiple inputs
{
Inter-organismic Mechanisms
{
Extra-organismic Mechanisms
Examples
{
Hunger
{
Thirst
{
Sex
{
{
{
{
Homeostasis
Negative feedback
2
Drives & Energy Balance
{
Homeostasis
z
Need
(e.g., for
food, water)
Hunger Brain Centers
tendency to keep a constant or
balanced internal state
Drive
(hunger, thirst)
Drive-reducing
behaviors
(eating, drinking)
Rest
Primary motives: hunger
{
Psychological factors in hunger
z
z
z
z
z
z
learning affects hunger
emotion affects hunger
incentives affect hunger
social situations affect hunger
commercials, time, and smells all affect
hunger
“stimulus control” and dieting: controlling
the cues to eat
Eating can be fun
Your brain
consumes 66%
(2/3) or your total
daily supply of
glucose
3
Hunger and Eating
The Physiology of Hunger
Stages of hunger
{
- Feel hunger in response to a homeostatic system
designed to maintain normal body weight and an
adequate nutrient supply
When glucose levels rise in the blood,
pancreas releases insulin
z
Body Chemistry
- Changes in body chemistry also affect hunger
- Increases in insulin diminish blood glucose, partly
by converting it to stored fat
- When blood glucose level drops, hunger increases
Glucostatic Theory - fluctuating levels of glucose
influence hunger states
Hunger and Eating
z
{
Insulin causes cells to store excess glucose
as fats and glycogen
Lack of hunger= decreased eating, lowers
glucose level.
Pancreas releases glucagon which
stimulates liver to convert glycogen into
glucose which enters the blood for
immediate energy needs.
z
The high ratio of glucagon to insulin
stimulates hunger. The cycle repeats.
Long Term Energy Balance
The lipostatic hypothesis
{
Fat tissue
z
z
Signals about body fat control hunger
motivation
{ Ghrelin, leptin (leptos means thin)
When mass of stored fat is too low, secreted
hormones stimulate hunger
Set Point Theory
{
{
genetically pre-determined ideal weight
fat cells determine hunger and satiety
4
Research on Weight Regulation
and Dieting
{
{
{
Fat cells are determined by genetics and food
intake
They increase with weight gain, but merely
shrink with weight loss - may stimulate hunger
Weight loss causes a decline in basal
metabolism
Fat cells
Normal
diet
High-fat
diet
Set Point Theory
{ Energy deficit =
↓ fat = lower leptin
{ Less binding to
hypothalamus =
more eating and
lower metabolic
rate
Return to
normal diet
Hunger and Eating
Hunger is a biological need
Eating behaviors reflect learned, cognitive, social, and
emotional influences, as well as biological needs
Learning
{ What we choose to eat is often driven by learned
preferences and aversions
Culture & Social Influences
{ influences how much we eat, what we eat, when we
eat
Emotional states
{ can reduce or increase drive to eat
5
Extra-organismic Mechanisms
Positive Incentive Theory
{
{
we eat three meals a day out of habit, or
because of external stimuli such as the time
of day, or the sight and smell of food.
Classical conditioning of food
Sensory-Specific Satiety
{
{
refers to the decrease in the pleasantness and
consumption of food after eating it to satiety –
the “all-you-can-eat Buffet” effect
Consumption influenced by taste, color,
flavour, texture, and shape of food.
Restrained vs. Unrestrained eating
{
{
Individual differences in emotional
responses related to food
Restrained (emotional) eaters:
{
Use food as a coping mechanism
Eat more when they experience stress
Tend to go on binges once restraint is broken
{
Non-restrained (non-emotional) eaters
{
{
{
{
Don’t use food as a coping mechanism
Less likely to eat more when stressed
Research
{
When placed in a stressful situation and given
access to high and low calorie food which
group ate more unhealthy food?
Eating Disorders and Disordered
Eating Habits
Anorexia Nervosa
(Too thin: BMI <17.5)
– Restricting Type
– Bingeing/Purging Type
Bulimia Nervosa
(Binge + inappropriate compensatory behaviour)
– Purging Type
– Non-purging Type
•periods of overeating, usually of highly caloric
foods, followed by vomiting, laxative use or
excessive exercise
Anorexia < prevalent than Bulimia
6