Lecture 5- Learning and the control of dietary behavior

Question 1

Why do we need to learn?

Answer 1

obtain sufficient food energy to meet requirements for maintenance, growth, and activity

obtain sufficient quantities of essential macro- and micro-nutrients

avoid ingesting harmful substances

Question 2

What are the 2 key things that humans need to do with food with regards to learning?

Answer 2

be able to exploit food resources when they become available

to know (learn) which foods are safe to eat and are good sources of nutrients and energy

Question 3

What is The omnivore’s paradox?

Answer 3

As omnivores, the most unselective eaters, humans are faced with a wide variety of food choices, resulting in a dilemma.

Arguably, modern food preservation and transportation technologies, this particular dilemma was resolved primarily through cultural influences.

These technologies have recreated the dilemma, by making available foods that were previously seasonal or regional.

Question 4

Gibson & Wardle (2003)

Answer 4

young children can discriminate against food according to their energy density; which is expressed through their preferences; they are orientated towards higher density foods

Question 5

Is taste a good predictor of energy density?

Answer 5

Sweetness is NOT a good predictor of energy content

Can’t rely on basic taste characteristics

INSTEAD learning plays an important role-we have to experience foods

Question 6

What is flavour preference learning?

Answer 6

Food (US) normally elicits salivation (the UR [unconditioned response])

But when CS (novel stimulus) and US are paired, the CS becomes able

to elicit a CR [conditioned response]

Question 7

Garcia- associative learning

Answer 7

can form an association between the sensory characteristics of a food and its post-ingestive affects

Question 8

What is special about conditioned taste aversions?

Answer 8

Showed that conditioned taste aversions could be seen over a 24hour lapse; unlike the traditional view about classical conditioning:

Conditioned taste aversions challenges:

The need for close temporal contiguity

AND the need several exposures for learning to take place

As you only need 1 exposure

Question 9

Can you be conditioned to avoid food?

Answer 9

Garcia demonstrated a clear predisposition to associate flavors with illness

Bait shyness (nausea and bait)

BUT Garcia found it is DIFFICULUT to from an association between sweet taste and pain

I.E. NOT every CS can form an association between US

Question 10

What are the 3 challenges of CTA?

Answer 10

Temporal contiguity (rapid learning within 24 hours)

Can occur after 1 exposure

Clear predisposition to associate flavours with illness (rather than associated stimuli)

Question 11

Sclafani (1997)

Flavor-nutrient learning

Answer 11

energy can reinforce changes in flavour preferences

Animals will learn an association between a novel flavor and how it might signal the infusion of nutrients drawn into the stomach VERY quickly

Question 12

F-N learning is abundant in animals…

Answer 12

Demonstrations of F-N preference conditioning are quite rare in humans

Question 13

Why is F-N learning rare in humans?

Answer 13

Evidence learning greater in children; perhaps between they have encountered fewer flavor?

Greater array of flavors inhibits learning ability to discriminate

Question 14

Lack of F-N learning…is it down to the issues in the western diet?

Answer 14

Lack of flavor nutrient experiments due to too many flavors

Western diets inhibited our ability to test different types of flavors

NO:

Look at Samburu – semi-nomadic pastoralists who have a less varied diet

FOUND:

NO evidence for flavor-nutrient learning thus perhaps variety of flavors does not account for the fact that we stop learning about flavors

Question 15

How has our diet different to hunter-gatherer populations?

Answer 15

Because historically humans not used to energy dense food; today we are constantly exposed to HIGH energy dense food which…

Has HUGE effects on ability to discriminate against very energy dense food

Question 16

Lack of F-N learning and physiology

Humans are poorly adapted to energy rich foods

We do not have the capacity to discriminate between energy density

Answer 16

Testing foods are far more energy dense that what we are naturally designed to be able to discriminate against

Thus, don’t have the physiology for it

NOT well adapted to discriminating energy rich foods

And in flavor-nutrient learning studies we are arguably exposing pps to very high energy dense foods

Question 17

Alternative: How else could we learn about Preferences?

Answer 17

Flavour-flavour learning – taking a ‘short cut’

Affective quality of the already liked flavor will rub off on the conditioned stimulus

Transfers affect from Unconditioned to the conditioned stimulus

If something is already liked and it is presented with something novel

You will learn to like it!

Question 18

Zellner

Answer 18

The flavors are presented in the absence of sucrose (taken away unconditioned stimulus) to show the transfer of affects

The flavor that was previously paired with the sweet tasting solution, is now more liked than cs-

Demonstrating a transfer of “liking”

Evidence of flavor flavor learning

Question 19

Zajonc (1968)

Answer 19

“Attitudinal Effects of Mere Exposure”

Simple, unreinforced exposure leads to increased liking for a stimulus.

Question 20

Chili

Stevenson & Yeomans (1995)

Answer 20

FOUND:

EVEN though low dose becomes increasing intense with regards to burn intensity

IT ALSO becomes increasingly LIKED

Argue:

There is a dissociation between the change in taste characteristics and intensity of burn sensation and liking

Attributed to an increased acceptance (NOT decreased intensity as actually more intense chilli was liked more) due to mere exposure effect

ONLY tells us about the mere acceptance of the consumption of a novel food NOT about the craving or desire of foods

Question 21

Awareness and dietary learning

Answer 21

FLAVOUR learning show that forms of CC conditioning occur outside conscious awareness

CS-US contingency awareness might NOT be necessary in:

▪ Flavour-flavour learning

▪ Caffeine conditioning

▪ CTA’s

Question 22

Dietary learning may be…

Answer 22

Unusual

Automatic

‘Primitive’

Dependent solely on CS-US presentation

Able to accommodate long CS-US contingencies