Describe and evaluate research into circadian rhythms (8+16)
Research into circadian rhythms has assessed the effects of isolating participants from external time cues (exogenous zeitgebers) on our 24 hour cycles, and suggesting that an internal body clock (endogenous pacemaker) creates a free running sleep/wake cycle rhythm of 25 hours.
* Case study of his own experiences in an underground cave for 2 months. Without any exogenous zeitgebers such as light or cues to guide him, his sleep/wake cycle generally adjusted to a 25 hour cycle, though sometimes changing dramatically up to 48 hours.
Aschoff and Weaver (1976)
* Designed a temporal isolation study by placing ...view middle of the document...
* Investigated the role of endogenous pacemakers, in particular the SCN, in the circadian rhythms of hamsters.
* Morgan removed the SCN in hamsters and found that their circadian rhythm disappeared.
* SCN was replaced by those of foetal hamsters, the circadian rhythm was re-established.
* Highly reliable, great contribution to understanding of the human brain and behaviour, evidence for the location of the SCN in the brain which controls circadian rhythms.
* Morgan’s research breaches ethical guidelines because lesions and permanent damage was inflicted upon the hamsters, made worse by the fact that the study cannot be generalised by humans because hamsters don’t share physiological properties with humans or even share similar circadian rhythm hours.
Other research has investigated possible 24 hour cognitive performance rhythms linked to the core body temperature cycle.
* It is lowest at around 4:30 am (36 degrees) and highest at 6:00 pm (38 degrees) with a slight trough after lunchtime.
Folkard et al (1977)
* Investigated the learning ability of young teenagers by asking them to recall a story a week after being read to (either at 9:00am or 3:00pm).
* The higher afternoon temperature group showed a superior recall and understanding, suggesting that long term recall is better with a higher body temperature.
Giesbrecht et al (1993)
* How temperature changes do cause changes in cognitive performance.
* Participants had their body temperatures lowered by sitting in cold water and were found to have a worse cognitive performance. However, no correlation can be ascertained due to other refuting evidence.
Hord and Thompson (1983)
* Tested cognitive performance in a more internally valid experiment (as opposed to a contrived laboratory experiment) and found no correlation.
* Suggests, higher temperature leads to increased physiological arousal and improved cognitive performance, therefore body temperature may not directly influence cognitive performance.
Circadian cognitive performance rhythms have real world applications in the field of education because it’s implied that learning would be more successful at particular times
* Reflected in PISA country education rankings with Spain scoring higher than England.
* The lack of reliability in this area however, means that caution must be taken when implementing applications until conclusive research has determined why students often yield conflicting results.
The main flaw of research into circadian rhythms is that studies often fail to take into account individual differences
* Within 24 hour rhythms, especially how people are far from ‘average’ given differing health, customs and socioeconomic backgrounds.
* Found how people in hotter countries, such as Mexico, take naps in the afternoon to avoid working in the heat and generally work until later on in...