Cognitive psychologists use four main Research Methods:
1. Laboratory Experiments: Lots of research in cognitive psychology happen in laboratories. Very scientific and reliable as you can have greater control over variables in lab. But this type of research doesn’t tell us much about the real world – had low ecological validity.
2. Field Experiments: Take place in natural situation (e.g. studies of memory or attention in a school environment), have more ecological validity, but less control over other variables.
3. Natural Experiments: Involve making observations of a naturally occurring situation. Experimenter has little control of the variables, and participants can’t be randomly assigned to conditions. Natural experiments have high ecological validity, but not entirely reliable as uncontrolled variables can affect results.
4. Brain Imaging: Can be carried out during cognitive task. E.g. MRI scans have been used to show blood flow in different brain areas for different types of memory tasks.
Milner et al – case study of HM – Provide support for the Cognitive Approach
Diagnosis: HM was a patient with severe and frequent epilepsy. His seizures were based in a brain structure called the hippocampus. In 1953, doctors decided to surgically remove part of the brain round this area.
Results: Operation reduced his epilepsy, but led to him suffering memory loss. He could still form short-term memories (STMs) but was unable to form new long-term memories (LTMs). E.g. read something over and over without realising that he had read it before. He also moved house had difficulty recalling the new route to his house. But he could still talk and show previous skills (procedural memory). From tests, they found HM’s episodic memory (for past events) and semantic memory was affected more than his procedural memory.
Gardner and Gardner (1969) – teaching ASL to a chimp – Cognitive psychologists apply Animal Research to Humans.
Method: Washoe, a chimpanzee, was raised like a human child and taught American Sign Language (ASL).
Results: By the end of the 22nd month of the project, Washoe had learnt at least 34 signs.
Conclusion: Development of language in the chimpanzee appeared to follow the same patterns as language development in children. Washoe learnt language at similar rates to children of the same age. Additionally, language acquisition seemed to require interaction with caregivers and communication in everyday situation. However, she did not learn grammar.
Evaluation: There are ethical considerations, in that Washoe was taken from the wild and deprived of other chimpanzees for companionship. There are also issues of external validity – it is not possible to accurately generalise results from a chimp to human children.
STM and LTM differ in terms of:
1. Duration – How long a memory lasts
2. Capacity – How much can be held in the memory
3. Encoding – Transferring information into code, creating a ‘trace’.
STM has a limited capacity and a limited duration
LTM has unlimited capacity and it is theoretically permanent
Peterson and Peterson – Duration of STM
Method: Participants were shown nonsense trigrams (3 random consonants, e.g. CVM) and asked to recall them after either 3, 6, 9, 12, 15 or 18 seconds. During the pause, they were asked to count backwards in threes from a given number. This was an ‘interference task’ – it prevented them from repeating the letters to themselves.
Results: After 3 seconds, participants could recall about 80% of trigrams correctly. After 18 seconds, only about 10% were recalled correctly.
Conclusion: When rehearsal is prevented, very little can stay in the STM for longer than about 18 seconds.
Evaluation: The results are likely to be reliable – it’s a laboratory experiment where the variables can be tightly controlled. However, nonsense trigrams are artificial, so the study lacks ecological validity. Meaningful or ‘real-life’ memories may last longer in…