Lecture 7 - Learning about Time

Question 1

Outline time in humans

Answer 1

Good estimating time periods, making judgements intervals shorter or longer
Sensitive day/night cycle
Distinguish periodic and interval timing

Question 2

Define briefly periodic timing

Answer 2

Learning responds particular time of day

Question 3

Define Interval timing

Answer 3

Learning is a response after particular interval of time

Question 4

Outline Carlson circadian rhythm periodic timing experiment

Answer 4

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

Question 5

Outline Roberts 1965 Cockroaches study

Answer 5

Removed visual cues cycle drifted until activity increased 15 hours before dusk.
Restoring visual cues produced gradual shift back to correct.
Light = zeitgeber

Question 6

Outline Bolles and Stokes 1965 study on rats

Answer 6

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

Question 7

Evidence physiological system provide 24 hour clock

Answer 7

Suprachiasmatic Nucleus (SCN) hypothalamus 
Metabolic rate SCN appears vary function day-night cycle 
Lesions SCN abolish circadian

Question 8

Evidence every cell has circadian rhythm all under control SCN

Answer 8

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

Question 9

Outline Interval Timing

Answer 9

CC: tone (20 sec) –> Food. Learn tone means food.

Response increase gradually to point food presented. Learnt about 20 second interval.

Question 10

What occurs if a stimulus keeps going and you omit food?

Answer 10

Peak procedure
Responding keeps increases.
After 20 seconds responding goes down, realises food not being delivered

Question 11

Outline Church and Gibbon 1982 study

Answer 11

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

Question 12

Outline Webers Law

Answer 12

Generalisation noticeable difference proportional to initial intensity of changed stimulus
Small amounts judged more accurately
Relative change critical

Question 13

Who investigated Scalar Timing Theory

Answer 13

Gibbon, Church and Meck 1984

Question 14

Outline Scalar Timing Theory Gibbon, Church and Meck 1984

Answer 14

Pacemaker emits pulses roughly constant rate

Stimulus presented switch operated and pulses accumulate working memory and begin time stimulus

Question 15

Outline Scalar Timing Theory Gibbon, Church and Meck 1984 Stage 1

Answer 15

Pacemaker records pulses per second
e.g. 5 seconds
Mental note that 5 seconds something important occurring.
DO not store perfectly = allow some distortion

Question 16

Outline Scalar Timing Theory Gibbon, Church and Meck 1984 Stage 2

Answer 16

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.

Question 17

Outline Scalar Timing Theory Gibbon, Church and Meck 1984 Stage 3

Answer 17

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.

Question 18

Outline the problem of no physiological evidence for pacemaker as a problem of Scaler Timing Theory

Answer 18

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

Question 19

Outline the solution of Behavioural theory of timing by Killeen and Fetterman 1988

Answer 19

Animal gets reward this stimulates behaviour.

Behaviour that is occurring when next reinforcer occurs becomes signal for that reinforcer

Question 20

Outline the potential problem with Scalar Timing Theory of conditioning and timing supposedly occurring same time yet controlled different learning mechanisms

Answer 20

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

Question 21

Why cant the Scalar Timing Theory not explain basic phenomena like blocking

Answer 21

Real time models try explaining timing
Work Rescorla-Wagner Model
However, stimulus assumed change over course presentation, allows animal learn about when reinforcer occurs