Lecture 7 - Learning about Time Flashcards
Outline time in humans
Good estimating time periods, making judgements intervals shorter or longer
Sensitive day/night cycle
Distinguish periodic and interval timing
Define briefly periodic timing
Learning responds particular time of day
Define Interval timing
Learning is a response after particular interval of time
Outline Carlson circadian rhythm periodic timing experiment
Rats with running wheel. 12 hour cycle light on and off. More likely run dark cycles.
Not innate when moved lighting time activity shifted.
Dim light when no light cues available they maintain behaviour approximately 25-hour cycle
Outline Roberts 1965 Cockroaches study
Removed visual cues cycle drifted until activity increased 15 hours before dusk.
Restoring visual cues produced gradual shift back to correct.
Light = zeitgeber
Outline Bolles and Stokes 1965 study on rats
Rats reared 19, 24 or 29 light cycles.
24 hours when light anticipate food coming and run more wheel
29 hours run before light changed, anticipating food even thought it wasn’t
Evidence physiological system provide 24 hour clock
Suprachiasmatic Nucleus (SCN) hypothalamus Metabolic rate SCN appears vary function day-night cycle Lesions SCN abolish circadian
Evidence every cell has circadian rhythm all under control SCN
Circadian variation sensitivity tumours to chemotherapy. Target key organ by giving chemo and max chemo giving it when organ most active
Sleep and circadian rhythm disruption
Visually impaired ensure they have enough exposure to light
Disruption responsible physical illness e.g. shift workers - heart disease, diabetes, infections, cancer
Mental illness - depression, schiz, bipolar
Outline Interval Timing
CC: tone (20 sec) –> Food. Learn tone means food.
Response increase gradually to point food presented. Learnt about 20 second interval.
What occurs if a stimulus keeps going and you omit food?
Peak procedure
Responding keeps increases.
After 20 seconds responding goes down, realises food not being delivered
Outline Church and Gibbon 1982 study
Rats lit chamber. House light went off various amounts time. If pressed lever after 4 seconds rewarded food.
Peak procedure = light too short didn’t respond, closer 4 seconds responding increased, after 4 seconds responding decreased
Outline Webers Law
Generalisation noticeable difference proportional to initial intensity of changed stimulus
Small amounts judged more accurately
Relative change critical
Who investigated Scalar Timing Theory
Gibbon, Church and Meck 1984
Outline Scalar Timing Theory Gibbon, Church and Meck 1984
Pacemaker emits pulses roughly constant rate
Stimulus presented switch operated and pulses accumulate working memory and begin time stimulus
Outline Scalar Timing Theory Gibbon, Church and Meck 1984 Stage 1
Pacemaker records pulses per second
e.g. 5 seconds
Mental note that 5 seconds something important occurring.
DO not store perfectly = allow some distortion
Outline Scalar Timing Theory Gibbon, Church and Meck 1984 Stage 2
Reinforcement occurs, pulses stop accumulating. Number pulses now stored reference in memory.
Some distortion.
After several trials several numbers stored reference.
Error each trial will not be the same.
Outline Scalar Timing Theory Gibbon, Church and Meck 1984 Stage 3
Use stored value reference memory to decide whether or not to respond on next trial.
Each trial animal compares number pulses with random value already stored in reference memory.
Done by comparator.
Outline the problem of no physiological evidence for pacemaker as a problem of Scaler Timing Theory
Could be series oscillators, each 2 states on or off. Series nerves/cells on and off cells. One set 12 hour cycle, another 6 hour cycle etc.
Entire pattern activation could be used determine exact time
Outline the solution of Behavioural theory of timing by Killeen and Fetterman 1988
Animal gets reward this stimulates behaviour.
Behaviour that is occurring when next reinforcer occurs becomes signal for that reinforcer
Outline the potential problem with Scalar Timing Theory of conditioning and timing supposedly occurring same time yet controlled different learning mechanisms
Calculate rate reinforcement during stimulus and rate reinforcement during background.
If first higher than second get
For example can get greater reinforcement in 15 minutes despite fewer reinforcers
Why cant the Scalar Timing Theory not explain basic phenomena like blocking
Real time models try explaining timing
Work Rescorla-Wagner Model
However, stimulus assumed change over course presentation, allows animal learn about when reinforcer occurs
