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Relevant Background informationexternal image taxi_trailer_03.jpg
  • Episodic Memory: Memory of autobiographical events (i.e. times, places)
  • Semantic Memory: General facts of the world (This study looked at semantic memory and the role the brain plays in the activation of this type of memory)

Aim
  1. To examine semantic topographical memory retrieval and to determine if recall of well established spatial layouts activates similar brain regions as noted in other studies.
  2. Examine topographical (landmarks, spatial layouts) semantic memory versus non-topographical semantic memory versus non-topographical semantic memory and see if common brain regions were activated.

Participant group
  • Licensed London taxi drivers
  • Must have 3 years of training and tests of spatial knowledge
  • 11 males participants
  • Ages 38-52

Research method
  • Lab Study

How was the data collected?
  • PET scans and verbal recordings

Procedure
  • Questionnaire (Areas of London which they were most familiar with, Movies that were common among all, Landmarks they had visited in person and could envision in their head)
  • Arrived for scans, participants were blindfolded and speech was recorded visually
  • Each task, one stimulus at a time
  • PET scans

Special equipment
  • PET scans

Results
  • All spoke about same amount of time
  • High accuracy on all tasks
  • Navigation task, routes chosen were similar
  • During tasks, subjects stated they visually noted the paths, landmarks, and movies

Conclusions
  • Routes: Activation of the hippocampus in topographic memory retrieval. Specifically the right hippocampus. Since real world environments were used, the study suggests that this may reflect the role of the hippocampus in high level spatial manipulation and decision making.
  • Landmarks: The main difference between activation patterns for routes and landmarks was that the right hippocampus was activated only in the routes task but not during recall of landmarks. The landmarks lacked a location within a large-scale spatial
  • framework and thoughts of navigation between them were not possible, again suggesting a role for the right hippocampus in the crucial complex stage of facilitating navigation in large-scale space.
  • Semantic memory: Except for cerebral activity, the brain regions activated during recall of movie plots was different from routes tasks. Most brain activity was on the left side of the brain.

Strengths
  • Real world routes and landmarks
  • All overly qualified (3 years training min.)
  • All from same area (familiar with routes)
  • Questionnaire

Weaknesses
  • Only male subjects
  • Only 11 subjects (more would have made it more accurate)
  • Conducted in a lab

Ecological Validity
  • No deception
  • No incentive to lie (no reward)
  • All asked same routes, landmarks, movies

Ethics
- Nothing ethically wrong with it (no harm/damage)