Learning & MemoryBy Aaron McCrindle & Ben Cooke

Behaviour

…can be regarded as any action of an organism that changes its relationship to its environment.

…is the particular way in which we respond to a detected stimulus.

By explaining why we respond to other people, organisms and situations in the way that we do, we can attempt to understand the behaviour of the individual.

Nature vs. Nurture

This is a well known psychological debate where arguments can be made…

…that behaviour is built into the genetic code of an individual and comes about instinctivelyor …that behaviour is developed through the detection, processing and recollection of external stimuli in response to our previous actions or the experience of another’s behaviour..

However, it is often considered reductionist to isolate how we behave into these two set categories.

But, by accepting that overall behavioural responses to the environment is affected by both nature and nurture, we gain a more holistic and accurate understanding of the cognitive functions of an organism.

Innate Behaviour• This is the ‘nature’ behaviour.

• It is determined by the "hard-wiring" of the nervous system. It is usually inflexible, a given stimulus triggering a given response.

• Taxis is the directed movement towards or away from a stimulus, which can be in response to light (phototaxis), chemical signals (chemotaxis), or gravity (geotaxis).

• Migration is an innate behaviour characterized as the long-range seasonal movement of animals; it is an evolved, adapted response to variation in resource availability.

Examples…YawningA yawn is a natural human reflex. It involves the inhalation of air, stretching of the eardrums, and is followed by a large exhalation of breath. One theory states that yawning occurs when a person’s blood contains an increased amount of carbon dioxide and needs oxygen; other theories state that it is a way of controlling brain temperature, blood pressure, alertness within a group (hence its contagiousness) or a territorial reflex so that organisms look larger and expose their teeth to scare other animals.

CryingCrying is an innate behaviour, as we demonstrate as soon as we are born in order to reduce emotional stress and to gain comfort socially, therefore it cannot be as a result of learned or habituated behaviour.

Vestibulo-Ocular ReflexVestibulo-ocular reflex (VOR) is a human reflex movement that stabilizes images on the retina. It accomplishes this by producing a rapid eye movement in the direction opposite to the head movement. Alcohol disrupts this reflex.

Mammalian Diving ReflexAs soon as the face hits cold water(<21C), the diving reflex is triggered in an attempt to maximize oxygen output. The human heart rate slows down by 10-25% and blood flow is constricted to the extremities. At extreme depths, the body intentionally allows fluid to fill the lungs and chest cavity to prevent organs from being crushed by pressure. The mammalian diving reflex greatly increases the odds of survival during accidental submersion.

Learned Behaviour• Behaviour that is altered as a result of the

experience of the individual.

• Riding a bike, eating habits, sports skills etc.

Habituation• Habituation is a reduction in an innate response to

a stimulus after repeated exposure.

• However, it can also be applied to learned behaviour as the extinction of a conditioned response.

• Sensitization is an increase in the response behaviour.

• A natural animal instinct is to protect themselves and their territory from any danger and potential predators or an unfamiliar stimulus

• An initial defensive response to a new stimulus is important because if an animal fails to respond to a potentially dangerous unknown stimulus, the results could be deadly.

• Despite this initial, innate defensive response to an unfamiliar stimulus, the response becomes habituated if the stimulus repeatedly occurs but causes no harm.

• An example of this is the prairie dog habituating to humans. Prairie dogs give alarm calls when they detect a potentially dangerous stimulus. This defensive call occurs when any mammal, snake, or large bird approaches them. However, they habituate to noises, such as human footsteps, that occur repeatedly but result in no harm to them. If prairie dogs never habituate to nonthreatening stimuli, they would be constantly sending out alarm calls and wasting their time and energy.

Models and Theories• The Sokolov model assumes that when a stimulus is

experienced several times the nervous system creates a model of the expected stimulus (a stimulus model).

• With additional presentations of the stimulus the experienced stimulus is compared with the stimulus model. If the experienced stimulus matches the stimulus model responding is inhibited.

• With additional presentations the stimulus model is improved; consequently there is no longer a mismatch and responding is inhibited causing habituation.

• However, if the stimulus is changed so that it no longer matches the stimulus model the inhibition of the orienting response is weakened, and an orienting response returns. Sokolov places the location of the Stimulus-Model within the cerebral cortex of the brain.

• The Groves and Thompson Dual Process theory • Two separate processes exist in the central nervous

system that interacts to produce habituation. • The two distinct processes are a habituation process and

a sensitization process. • The dual process theory argues that all noticeable stimuli

will elicit both of these processes and that the behavioural output will reflect a summation of both processes.

• Groves and Thompson hypothesize the existence of two neural pathways an “S-R pathway” involved with the habituation process, and a ”state pathway” involved with sensitization. The state system is seen as equivalent to a general state of arousal.

Classical ConditioningStage 1: Before Conditioning:

• Unconditioned stimulus (US) produces an unconditioned response (UR) in an organism. In basic terms this means that a stimulus in the environment has produced an innate response.

Stage 2: During Conditioning:

• During this stage a stimulus which produces no response (i.e. neutral) is associated with the unconditioned stimulus at which point it now becomes known as the conditioned stimulus (CS).

Stage 3: After Conditioning:

• Now the conditioned stimulus (CS) has been associated with the unconditioned stimulus (US) to create a new conditioned response (CR).

•John Watson•Ivan Pavlov

Watson

• Little Albert was a 9-month-old infant who responded with no fear to various animals as stimuli and was a healthy and stolid child.

• But he innately responded by fearing and crying to a loud noise.

• Conditioning: The white rat was presented and when Albert touched it a loud bang was made behind his head.  This was done 7 times over the next 7 weeks and each time Little Albert burst into tears.

• By now little Albert only had to see the rat and he immediately showed every sign of fear. He would cry (whether or not the hammer was hit against the steel bar) and he would attempt to crawl away.

• Over the next few weeks and months Little Albert was observed and 10 days after conditioning his fear of the rat was much less marked. This dying out of a learned response is called extinction. However even after a full month it was still evident.

Pavlov• Conditioned dogs to salivate when they heard a

bell ring. (Also done on children too)

Operant ConditioningPositive Reinforcement• Skinner showed how positive reinforcement worked by placing a hungry rat in his Skinner box. The box contained a lever in the

side and as the rat moved about the box it would accidentally knock the lever. Immediately it did so a food pellet would drop into a container next to the lever.

• The rats quickly learned to go straight to the lever after a few times of being put in the box. The consequence of receiving food if they pressed the lever ensured that they would repeat the action again and again. – Strengthens (conditions) behaviour.

Negative Reinforcement• Negative reinforcement is the removal of an adverse stimulus which is ‘rewarding’ to the animal or person. Negative

reinforcement strengthens behaviour because it stops or removes an unpleasant experience.• Skinner showed how negative reinforcement worked by placing a rat in his Skinner box and then subjecting it to an unpleasant

electric current which caused it some discomfort. As the rat moved about the box it would accidentally knock the lever. Immediately it did so the electric current would be switched off.

Punishment• Punishment is defined as the opposite of reinforcement since it is designed to weaken or eliminate a response rather than

increase it. The rats could be punished with an electric shock for not moving the lever or have their reward (food) removed. Difficult to distinguish with negative reinforcement.

Scoring a goal:

• Positive Reinforcement: Crowd celebrating, good feedback from coach.• Negative reinforcement: Crowd booing until, you score the goal.• Punishment: If you miss your shot, the crowd will boo and coach will shout at you.

•Thorndike•BF Skinner

Law of effect• Thorndike showed how cats became better at

navigating out of a puzzle box as the satisfaction of escaping acted as a reward to condition the behaviour.

Bandura

• Behaviourism: Input → Output

• Behaviourism + Cognition = Social Learning Theory

• Social Learning Theory: Observation → Attention, Perception, Retention, Modelling, Motivation, Repetition → Output.

• Vicarious Reinforcement: Imitating a model's behaviour because they have been reinforced to do the behaviour (Seeing someone else be rewarded and so copying their behaviour).

• Extends to symbolic (eg TV) influences.

• Bandura showed how model’s encourage children to be more violent to Bobo dolls.

• Both physically and verbally.

Memory at the cellular level• Memories are stored by strengthening synapses between neurons,

certain synapses are encoding a memory. • Part of strengthening a synapse involves making new proteins. Just

like with exercise, when new proteins must build up muscle mass, synapses must also make more protein when recording memories.

• The production of new proteins can only occur when the RNA that will make the required proteins is turned on.

• Until then, the RNA is "locked up" by a silencing molecule, which is a micro RNA.

• When something comes into your brain -- a thought, some sort of stimulus, you see something interesting, you hear some music -- synapses get activated.

• One of the proteins wrapped around that silencing complex gets degraded.

• Then the RNA is free to synthesize a new protein.

• Brain areas involved in the neuroanatomy of memory such as the hippocampus, the amygdala, the striatum, or the mammillary bodies are thought to be involved in specific types of memory. For example, the hippocampus is believed to be involved in spatial learning and declarative learning, while the amygdala is thought to be involved in emotional memory.