Operant conditioning: Reinforcement and behaviour modification Flashcards
Schedules of reinforcement-
Continuous and partial reinforcement
Continuous = reinforcer always follows a behaviour
- Continuous reinforcement, e.g. pay a child every time they wash up. effects do not last (children paid regularly for chores do not do them for long)
Partial = reinforcement is irregular
- Partial reinforcement, vary either the ratio of behaviour to reinforcement or the interval between reinforcements. Either can be fixed or variable (ranges around a mean time).
Partial schedules are written as F (fixed) or V (variable) with a number indicating the ratio or interval . For example, F13 is a fixed interval of 3, meaning that three time units must pass before another response can be rewarded. So a rat on F13 would wait 3 minutes after pressing the bar before it can get another reward.
Reinforcement schedules
-fixed ratio (FR)
—–and—–
-Variable ratio (VR)
FR schedule- reinforcer is given after a specified number of behaviours, e.g. pay a child every seventh time they wash up.
VR schedule- reinforcer is given after an unpredictable number of behaviours varying around a mean value, e.g. a child on variable ratio of 3 (VR3) may get paid after 1.3 or 5 for instances of washing up (1+3+5=9 divided by 3 gives the mean of 3). VR schedules produce behaviour that is hard to extinguish (stop).
Reinforcement schedules
-Fixed interval (FI)
—and—-
Variable interval (VI)
FI schedule- time between reinforcers is constant, e.g. pay a child at the end of the time interval if he has washed up once or more in that interval.
VI schedule- time between reinforcers varies around a mean length of time. Only one behaviour per interval is needed for reinforcement, e.g. pay a child at the end of the period if he washed up once or more in that interval, but the interval varies in length. VI schedules produce the most consistent behaviour.
Behaviour modification
- Modifying behaviour
( using operant conditioning to change behaviour)
-Reinforcement is systematically used to increase a desired behaviour.
-Ford et al used helmet sensors to assess head-impact (i.e. injury) in American footballers. Mentors gave reinforcement to high-risk players. Mean impact intensity dropped by 3.9% overall and by 4.7% on the top-of-head (particularly dangerous), so behaviour modification improved safety.
Behaviour modification
-Shaping
(reinforcing successive approximations to a target behaviour)
- Starts by reinforcing behaviour which is vaguely like target behaviour, then reinforcement only continues each time the behaviour is a step closer to the target behaviour.
-Shaping in language acquisition- infant babbling initially reinforced by adult attention/praise, but reinforcement only continues if the child then produces recognisable words (then sentences).
A strength is support from human and animal studies
-Hundreds of lab and field experiments have compared the effects of different partial reinforcement schedules on animal and human learning, with results consistently showing the properties of these schedules.
- For example, Latham and Dorsett found mountain beaver trappers responded better to variable ratio pay ( they received $4 for an animal if they also correctly guessed the colour of a marble) than fixed ratio Pay (they received $1 per animal)
-This means that there is a firm evidence base supporting the properties of partial reinforcement in both human and non-human animal learning.
A weakness is reinforcement schedules ignore intrinsic motivation
-Reinforcement properties provide a detailed account of extrinsic motivation (the effect of ‘outside’ factors) when someone else offers us a reward.
-But our behaviour is also a result of intrinsic (inside) motives. For example, at work we can be just as motivated by interest and enjoyment (intrinsic) as by extrinsic rewards, however well they are scheduled.
-This shows that reinforcement properties only provide a partial explanation for human motivation.
Application : Treating inappropriate behaviour
-Behaviour modification systems have been used to treat a range of mental health problems, from schizophrenia to autism spectrum disorder (ASD).
-For example, Lovaas therapy involves intensive reinforcement (including shaping) to normalise aspects of behaviour in children with ASD)
- This shows that behaviour modification Is of practical benefits to clients
Competing argument
Although behaviour modification techniques are open to abuse they are not inherently abusive- In most cases therapist and client agree on what behaviours they are working towards. Where this is not possible because of the clients cognitive or communication abilities, therapists need to give careful consideration to ethical issues
