What are the Gallagher-Baker indices in Water Maze?

Developed for Michela Gallagher in 1998

The rationale of these proximity measures is that the subject might reach the platform with moderately low latency & path length, even though it does not know where the platform is, just by using a sweeping search. The measure is low (good) when the subject knows approximately where the platform is (or was), and spends most time searching near to the platform position. Higher values indicate less knowledge.

 Gallagher Proximity Measure:
As described in the fourth paragraph of the ‘Procedure’ section of the 1993 Gallagher-Burwell-Burchinal paper, this is the average distance of the subject from the platform, corrected for start point using the procedure outlined in the same paragraph, i.e. using the average swim speed for the trial and removing the time required to swim at that speed to the platform position, from the beginning of the trial data, so as to exclude that part of the trial from the measure.
In the above paper this was used for probe trials.
Gallagher Cumulative Measure:
This is the sum of the distances, corrected for start point using the procedure outlined above. In the above paper the cumulative measure was used for training trials.
The above measures were calculated using the 1 second averages of the distances of the subject from the goal.
Gallagher by Segments:
This gives you a record of these 1 second averages, i.e. the average distance from the platform position for each second of the trial. So for a 60 second trial you will have 60 measurements, each one being the average distance for that second, as described early in the fourth paragraph of the ‘Procedure’ section of the above Gallagher-Burwell-Burchinal paper.
The above are also known as the The Gallagher Learning Index.

The Gallagher-Baker indices are specific refinements of the above.

  • The Gallagher-Baker proximity indices are corrections of average proximity, adjusted for the varying start point and with the higher sample rates achievable with automated tracking, so as to give greater accuracy.
  • The Global Gallagher-Baker Proximity Index is the average distance in meters from the platform over the whole trial, corrected for start point, and using every sample point for distance from platform, rather than 1 second averages. This makes it a more accurate equivalent of the Gallagher global measure above.
  • Cumulative Gallagher-Baker: The sum of all the distances used in the Global Gallagher-Baker Index, adjusted for the sampling frequency so as to be equivalent to (but more accurate at higher sample rates than) the Gallagher cumulative measure above.

These are distinct from The Gallagher Learning Index described in the 1993 paper and you should cite this permalink in any publication using these measures rather than that paper if you are using these measures.

Date Published: July 2017

MLA.  Hawthorne, E. L., & Baker, M. R. “What are the Gallagher-Baker indices in Water Maze?” Behavioral Tracking Knowledgebase., May. 2017. Web. 31 May 2017. http://hvsimage.com/permalink/gallagher-baker-indices/

APA. Baker, M. R.  (2017, May). What are the Gallagher-Baker indices in Water Maze? Retrieved from http://hvsimage.com/permalink/gallagher-baker-indices/

Chicago Hawthorne, Elizabeth & Baker, Mark. “What are the Gallagher-Baker indices in Water Maze?”, HVSImage.com. http://hvsimage.com/permalink/gallagher-baker-indices/ (accessed May, 31, 2017).