Habituation and classical conditioning Flashcards
(32 cards)
What are 3 possible definitions of learning?
Acquisition of information/skills
Acquisition of knowledge - internal representations
Long-lasting change in behaviour as result of experience
How can memory be viewed?
As ability to REMEMBER things or mental record of experiences
It is the PROCESS by which we code, store and retrieve info about our experiences
How and memory and learning connected?
Form a very integrated system - when we learn something we need to be able to store and retrieve it
What is reflexive behaviour and what are 4 key examples?
Series of fixed patterns of behaviour that guarantee adaptive responses to particular stimuli:
Grasp reflex - palmar grasp reflex when item placed in infant palm, involuntary flexion; after 6 months replaced by voluntary grasping
Walking - when soles of feet touch flat surface even newborns will place one foot in front of the other
Moro reflex - present up to 4 months, response to sudden loss of support - spreading out arms, unspreading arms, crying all involved
Babinski reflex - When sole of foot stroked the big toe moves upwards and other toes fan out, absence of descending inhibition (in an older child this is abnormal, should curl toes instead)
What did Descartes assume about reflexes?
Work in a very simple mechanistic fashion, no learning involved as response so immediate
What is the Bell-Magendie law?
Describes reflex arcs - anterior spinal nerve roots contain only motor fibres while posterior are only sensory, so in this way impulses can only be conducted in one direction
By this law, if reflexes do depend on the simple arc, they should be invariant i.e. occur whenever the eliciting stimulus present - reflexes would result in FIXED AND AUTOMATIC behaviour
What actually happens with reflex responses?
In many circumstances responses are not simply fixed and automatic - learning can override the primitive reflex response e.g. through habituation
Interneurons/association neurones are key to understanding this
What do we see in habituation?
For example, a new and intense sound produces a startle response in a rat, measurable by degree of movement - intensity of the jumps made
Rat actually stops responding when stimulation is repeated, and we see reduction in magnitude and frequency of the response as trials continue
What is the importance of DISHABITUATION?
Provides evidence against idea that habituation is simply overstimulated and fatigued muscles/neurones
- An unexpected stimulus e.g. light rather than the loud sound will restore the reflexive response when the sound is then played again
What does dishabituation indicate?
Reflex arc alone cannot account for habituation - evidence of modulatory inhibition from upper levels of NS (transmitted through interneuron)
We call this NON-ASSOCIATIVE LEARNING
What was Leaton’s experiment into the temporal course of habituation?
Leaton (1976) presented tone to rats and measured startle response - phase 1 (days 1-11) was one trial every 24hr (long-term habituation), phase 2 was 240 trials once every 3 seconds (day 12, short-term habituation) and phase 3 (days 13-15, spontaneous recovery) was one trial every 24 hr
Results indicated larger habituation effect on phase 2 as startle responses significantly reduced - magnitude increased again in phase 3 but not to same level as in phase 1
What did Leaton’s experiment suggest?
Massed presentations of eliciting stimulus result in full short term habituation which vanishes after a rest time (Spontaneous recovery)
Long-term habituation is more likely with widely spaced stimulus presentations and is retained for long periods
Provides some insight into how organisms store and retrieve info - temporal course constitutes simple model for short and long term retention of information processes; reflexes changed via experience and learning, startle reflex essentially diluted due to memory formation
What are the key components of classical conditioning?
Neutral stimulus i.e. tone (only response is a head turn)
Biologically relevant stimulus i.e. food (response is salivation)
After learning i.e. pairing tone with presentation of food, the tone becomes a CONDITIONED STIMULUS because it provokes the salivation response even in absence of food i.e. provokes the CONDITIONED RESPONSE
What is meant by excitatory classical conditioning?
When conditioned stimulus has positive relationship with unconditioned stimulus i.e. CS comes to predict the occurrence of the US, leading to the conditioned response
What is meant by inhibitory classical conditioning?
If CS prevents occurrence of CR the CS is known as an inhibitory CS or conditioned inhibitor
E.g. if dog trained to salivate to tone (CS) and then a light is presented simultaneously with the tone but no food given. The tone will signal absence of food after repeated trials - the key is that excitatory conditioning does need to have occurred first to allow conditioned inhibitor to mean anything
What are the 2 types of excitatory learning?
Appetitive and aversive
What is appetitive conditioning?
A form of associative learning by which new rewards are learned and are imbued with motivational salience - neutral stimuli acquire a new motivational significance through association with reward
e.g. if use food as US, see normal alimentary behaviour in response, can use approaching response to measure learning during CS presentation e.g. associating a light with presence of food
Initially rat won’t enter feeder much following light, but after repeated trials associating it with food, responses increase
What is aversive conditioning?
Use of something unpleasant or punishment to stop an unwanted behaviour
e.g. taste aversion conditioning - animal drinks flavoured solution (CS) but is then poisoned producing mild sickness (US); when subsequently offered the CS again it will avoid drinking it
It is the reduced consumption of solution that is a reliable index of associative learning
What is another example of aversive conditioning?
In flatworms - shock (US) administered causing flatworm to shrink up
When US paired with light (CS), repeated exposure eventually results in shrinkage occurring just in response to light
Associations only form when stimuli close enough together
What question can be asked about inhibitory conditioning?
In inhibitory conditioning, nothing follows the stimulus i.e. the tone doesn’t signal anything of biological relevance
The question is, has any learning actually occurred - is the tone just meaningless or is it actively signalling absence of something?
What was the experiment conducted by Wasserman, Franklin and Hearst?
Pigeon in a box with an illuminated disk, which acquires CS properties when associated with food - approaching and pecking disk indicates excitatory learning
Group 1 - light associated with food
Group 2 - light and food presented randomly so no association
Group 3 - food NEVER associated with light (inhibitory learning condition)
Measured time spent close to light - in group 1 it was 10/10 seconds, group 2 was 5/10 seconds so no learning and random behaviour, while group 3 was no seconds - implies inhibitory conditioning did occur and they learned the association with absence of food
What is the problem of silent learning?
Inhibitory CS often provokes response opposite to response elicited by excitatory CS, but sometimes inhibitory properties of CS are not evident - some behaviours are not as obvious as withdrawal from an illuminated disk, some may appear as ABSENCE of a behaviour so it isnt clear whether there has been learning or not
What is the purpose of a summation test?
To find whether an animal has learned something after inhibitory training
Control group = tone is excitatory CS, producing 10ml saliva; light is neutral as no inhibitory training –> no effect, presence of neutral stimulus doesn’t affect magnitude of excitatory response i.e. same amount of saliva due to tone in presence/absence of light
Experimental group = Tone is excitatory CS, but light is inhibitory CS after inhibitory training –> inhibits salivation, counteracts excitatory response and when light shown with tone only 5ml saliva produced
What is a retardation test?
For example, light becomes an inhibitory stimulus signalling absence of food
When try to pair inhibitory CS with food, it should take longer to make association if inhibitory learning has indeed occurred (have to change inhibitory neural connections)
Pre-existent inhibitory link RETARDS the acquisition of an excitatory link
