Background:
Semantic memory – concept-based knowledge in our long-term memory. Helps to do things like give a meaning to otherwise meaningless sentences or words by recalling information (e.g. shades of colours).
Episodic memory – specific and personal knowledge = recollection of our past experiences and specific events that happened.
Topographical memory – the ability to remember routes previously used and recognize familiar places.
Sequencing memory – the recollection of experiences and events in an ordered sequence.
Hippocampus: a part of the brain’s limbic system that is involved in memory processes. Humans/ animals have two hippocampi, on either side of the brain.
Aims:
To investigate:
- Whether there are specific brain regions that are responsible for semantic topographical memory.
- Whether there were brain functioning differences between tasks that involved topographical and non-topographical memories.
- If these two types of memories were affected by whether the memory was a sequence of logical events or not.
Method:
Sample:
- 11 right-handed males, aged 38-52.
- Taxi drivers in London.
- No history of psychiatric or neurological illness.
- Average time working as a taxi driver was 14.55 years – shortest time was three years.
- They all gave informed consent – volunteer PPs.
Design:
Prior to experimental tasks, complete a questionnaire about:
- Areas of London they were familiar with.
- Films they thought they were familiar with from a list 150 since 1939.
- Which 20 world-famous landmarks they could visualize in their minds and visited.
Six tasks performed twice – only 5 relevant to study (repeated measures design):
- Describe the shortest route between a starting point and destination in London (T and S).
- Describe a landmark known to the drivers in terms of features, appearance. (T and -S)
- Describe the plot of a film between two given points in the film (-T and S)
- Describe individual frames of some famous films – imagery and characters. (-T and -S)
- Repeat two sets of four-digit numbers.
Repeated measures design – tasks were counterbalanced.
| Tasks completed verbally – blindfolded and undergoing PET brain scans (to see which types of brain are active during specific tasks).
12 times per participant – received H2150 over 20-second period, followed by 20-second saline flush. Independent variable: the stimuli (routes, film plots, landmarks and film frames) Dependent variable: The brain activity |
Procedure:
After questionnaire – PPs underwent a PET scan.
Pilot study using non-taxi drivers – shown research team when to present each stimulus per tasks.
Each task lasted 90 seconds, with 8 minute gaps in-between. – 12 tasks in total.
Drivers debriefed when study was finished – MRI scan taken.
Results:
- All PPs spoke for same time – high level of accuracy in all tasks.
- The routes chosen by PPs were very similar in navigation tasks.
- During tasks, PPs could visualize the paths, landmarks and films.
- Regardless of experimental task, the cerebellum and left temporal lobe became activated.
- Right hippocampus only activated during Routes recall.
- Retrieval of landmark and route information activated similar regions.
| Task | Region of brain activated |
| Route in London | Extrastriata regions,
medial parietal lobe, posterior cingulate cortex, Para hippocampal gyrus, right hippocampus. |
| Landmarks | Posterior cingulated cortex
Medial parietal lobe Occipito-temporal region Para hippocampal gyrus |
| Films | Left frontal regions
Middle temporal gyrus Left angular gyrus |
Conclusion:
The regions of the brain used in semantic topographical memories are like those used in previous studies. The right hippocampus has a strong role sequential route planning. This seems to store information about routes in a sequence, especially those that have developed over a long period.
Strengths:
- Very high level of control: the experimenters had a large amount of control over variables which decreased the chance of external factors affecting the findings. All participants were blindfolded, speech was recorded, stimuli were the same for all participants and procedure was standardized.
- Good ecological validity: Even though the experiment was in a laboratory, the tasks were designed in such a way that they were like real life. Therefore, the participants’ behaviour might have been true to life.
- Replicable: The entire procedure was standardised – same way for all PPs. Therefore, it can be replicated easily and the reliability can be checked.
Weaknesses:
- Unrepresentative sample: The experiment only studied middle-aged men from London, who had an average of 14 years’ experience. Therefore, the results cannot be generalised to the entire population.
- No women: the results are gender biased because the study only researched men. Therefore, the the findings cannot be generalised and applicable to women.
- PET only shows blood flow or glucose metabolism
CIE A Level Psychology 