Lec 5 - Learning

Question 1

What are the nutritional problems for the omnivore?

Answer 1

1) obtain sufficient food energy to meet requirements for maintenance, growth, and activity
2) obtain sufficient quantities of essential macro- and micro-nutrients
3) avoid ingesting harmful substances

Question 2

what does rozin argue is the driving force for cognitive evolution?

Answer 2

The omnivore’s paradox…
The huge variety of potential foodstuffs available precludes any genetic pre-disposition to like or dislike anything beyond those basic signals which act as reliable predictors of relevant and unambiguous postingestive effects.

The need to identify harmful or beneficial food resources a major driving force for cognitive evolution.

Question 3

Gibson and wardle found..

Answer 3

Children discriminate fruits and vegetables based on their energy density, they prefer higher energy foods

Question 4

what do babies do to sucrose vs quinine?

Answer 4

rhymic tongue protrusions to sucrose and gapes to quinine, almost an atttempt to get it out of the mouth.

Question 5

what is the relationship between taste and nutritional content?

Answer 5

= Sweet taste intensity was associated with mono- and disaccharides, but not energy content.

Salt taste intensity was associated with sodium and less so protein, fat and energy content.

Key point is that we cannot rely on basic tastes

Question 6

describe classical conditioning

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

what were the three challenges from CTA (conditioned taste aversion?)

and what assumption do they challenge?

Answer 7

1) Temporal contiguity predicted that learning should proceed when the two events occurred closely together in time, yet CTA could be seen even with 24 hours elapsing between flavour exposure and induced nausea
2) CTA can occur after a single flavour-illness experience, whereas most examples of conditioned associations develop progressively over a number of learning trials.
3) (most important of all) There is a clear predisposition to associate flavours with illness rather than other associated stimuli

A violation of the “equipotentiality assumption”

Question 8

what is flavour consequence learning?

Answer 8

It broadens the original discovery of CTA into a generalised model for understanding changes in liking and preference based on the idea that we are pre-prepared to associate flavours with post-ingestive consequences.

Question 9

what is flavour nutrient learning?

who demonstrated it?

Answer 9

Associations between the orosensory properties of the ingested food or drink (the flavour CS) and positive consequences of nutrient ingestion (the UCS) lead to acquired liking for the flavour
Best demonstrated in animals by Sclafarni for example

Question 10

Sclafarni - animals..

Answer 10

Flavour nutrient learning-

Animals quickly learn signal of new flavour and orientate more around CS+ to get novel and nutrient infused liquid

Question 11

how do you test FNL in humans?

and what is the literature like?

Answer 11

disguise calorie intake, give two novel flavours and add calories to one of these. Flavour is counterbalanced so it is not to do with flavour it is to do with learning.
After time, the exposure to these you may expect people to prefer the food that has been infused with starch/calories even tho flavours are the same.

Evidence for adults it patchy. More success looking at flavour nutrient learning in children. Maybe because they have experienced fewer flavours and as adults perhaps they have learnt so many that they are unable to learn novel associations

Question 12

what did Yeoman’s review report on FNL?

Answer 12

Overall, 9/14 (64%) of studies that report changes in liking or preference provided evidence for preference learning

Question 13

Brunstrom et al - Samurai study

Answer 13

Flavour nutrient learning was studied in samurai in people who had never experienced western diet and they didn’t have a diverse diet (milk, cheese, blood goat etc)
Samburu participants consumed a sensory-matched portion of either a novel low or higher energy-dense semi-solid food on two training days, and an intermediate version on day 3. Before and after each meal we measured appetite and assessed expected satiation and liking for the test food.
No evidence was found for flavour nutrient learning

=Learning is not inhibited by food abundance (common in a Western diet)

Question 14

Richardson et al 1996

Answer 14

Provided evidence that conditioning does occur in adults..
two groups either non/low consumers verse regular caffeine consumers. They received either caffeine and novel juice, or placebo and novel juice. Pp who experienced the CS+ (CS paired with US) had greater preference on novel fruit juice than those in CS-, these tended to be regular consumers

Question 15

what happens to food preferences in adults for energy density?

Answer 15

In low energy dense there was replication of findings from Gibson and Warner on children. There is linear relationship between preference and energy density. But when this is extended to much more energy dense foods this is greatly deteriated. Humans are poorly adapted to energy dense foods.

Question 16

what is evolutionary discordance

Answer 16

modern human physiology is poorly adapted to evaluate foods that have a historically unusual (high) energy density

Question 17

What is flavour flavour learning?

who was first to demonstrate it in humans?

Answer 17

Can be demonstrated in a single session (unlike flavour nutrient learning) .. it is a short cut!

In ‘flavour-flavour learning,’ a neutral flavour (CS) is paired repeatedly in close temporal proximity with an already liked flavour (US). After this period, the valance of the CS is found to shift in the direction of the US.

The affective quality of already liked flavour transfers to US to CS.

Zellner first to demonstrate in humans

Question 18

Zellner et al 1983 study

Answer 18

First demonstration of flavour-flavour learning in humans
pair something with surcose (CS+) or without (CS-) then after lots of conditioning in a single test session you test them both without the unconditioned stimulus (the sucrose) what you find is that..
=the thing that was previously paired with liked stimulus (sucrose - the CS+) is preferred more than the one that was not paired for liked flavour (CS-).

Question 19

what is mere exposure and who investigated it ?

Answer 19

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

Question 20

Stevenson and Yeomans study

Answer 20

Looked at what happens when you expose ppl to taste of chilli. There were two diff concentrates of chilli, low and high intensity, in the low intensity there is a slight increase in burn, if you look at liking over 5 sessions you see that even tho the low intensity burning increases, the liking increases,
There is increased acceptance through mere exposure.

Question 21

how many exposures do children need to accept food?

Answer 21

20

Question 22

what makes these different to conditioning?
Flavour-flavour learning

Caffeine conditioning

CTA’s

Answer 22

contingency awareness isn’t necessary (don’t need to learn when to predict future event) Therefore explicit learning isnt necessarly.

‘contingency awareness’ refers to the capacity to articulate the contingency between a specific CS and US after exposure to their pairing.

Question 23

So dietary learning is…

Answer 23

Unusual

Automatic

‘Primitive’

Dependent solely on CS-US presentation

Able to accommodate long CS-US contingencies

Question 24

What does andy field argue?

Answer 24

dietary learning is so important that it makes sense for associations to be formed spontaneously, without the need for conscious control.

Question 25

which broadens the original discovery of CTA and involves post-ingesetive associations..

energy can reinforce changes in flavour preferences is related to…

Answer 25

flavour consequence learning

flavour nutrient learning

Question 26

chemotherpay demonstrates what?

Answer 26

conditioned taste aversions