Time Flashcards
Periodic timing vs interval timing
Learning to respond at a particular time of day vs interval timing i.e. a time interval
24 hour clocks in animals…?
Some evidence of internal clocks e.g. rats @25hr and cockroaches just under 24hr. But need light as a zeitgeiber.
Would rats born on mars have different light cycles?
Rats raised on different time cycles e.g. 19hr didn’t learn about it so well
Which physiological region originally thought to be responsible for internal clocks? Metabolic rate…? Lesions…?
Suprachiasmic nucleus (hypothalamus)
Metabolic rate shown to vary as a function of the day night cycles.
Rats with SCN lesions lost circadian regularity
More recent research?
Every cell in body has a circadian rhythm, controlled by the SCN
What medical use does this theory of cell timing have?
Chemo treatment
Disruption to circadian rhythm observed in which MH/clinical conditions?
Alzheimer’s, depression, schizophrenia, bipolar etc.
Explain peak procedure studies and how this relates to Weber’s law
Peak procedure = animals trained that food will come after eg 20s. Responses peak and then decline. You get a steeper curve when stimulus expected after 2s not 8s. due to weber’s law ΔI / I = k i.e. change in strength/og strength = k = just noticeable change.
Scalar timing theory
In summary, body keeps track of how long stimuli are presented. When stimulus next occurs, compares difference between current and old times as a proportion of the old time i.e. WM-RM/RM
Problems with scalar timing theory
- No evidence of pacemaker
- Behavioural explanation e.g. series of behavioural events
- Some theories explain both timing and conditioning e.g. Gibbon and Balsam 1977 – animals compare rate of reinforcement during stimulus vs during background. If higher => conditioning
- Real time models ~ like regular conditioning theories except stimulus assumed to change over course of presentation => animal can learn about when a reinforcer occurs.
