Wednesday, April 4, 2012

Mental Rotation in Preschoolers

Kids and spinning - a random
unrelated picture
I recently came across an interesting paper by Ping, Ratliff, Hickey, & Levine called Using Manual Rotation and Gesture to Improve Mental Rotation in Preschoolers that might have some implications for my own research. If you're so inclined you can grab a copy of the paper here.

Ping et al's research takes its orientation from studies that show that Mental Rotation is in some respects linked with motor processes, as well as research that shows that propensity to gesture during an MR task is positively correlated with  MR performance (I'll be covering this research soon).

The aim of the study was, then, to investigate the effectiveness of two different training methods on MR performance. The experiment had a standard pre post control design - 63 four year olds were randomly assigned to one of three conditions (two experimental conditions and a control condition) and were administered pre and post-tests assessing their speed and accuracy during a Mental Rotation task.

 The first training condition presented the children with two images of an animal - one of the images was presented in an upright orientation (i.e. the animal was on its feet) while the other was rotated around its centre at one of four different orientations. The children in this condition were then required to bring the rotated image into the same orientation as the upright image by using a joystick that would actually rotate the image clockwise or anti-clockwise in response to the children moving the joystick left and right.
 The second training condition was almost exactly like the first except instead of using a joystick to bring the rotated image into the same orientation as the target image, the children were asked to reach for the image on the screen, pretend that they were grabbing and then rotating the image to bring it in line with the upright image.
Finally, the control condition spent their time performing a task that didn't involve rotation.

The pre and post tests were a more or less standard 2D version of the Shepard-Metzler style MR test - but using images of animals instead of the usual collection of blocks or polygons that are used in these kinds of tests. As well as the Child Mental Transformation Task (CMTT), which was used to measure transfer.

The results were rather interesting (especially point 3 below) - here's a summary:
  1. Accuracy and speed improved significantly across all three groups - this is standard stuff, MR tends to have a serious practice-effect.
  2. Accuracy improved significantly on the gesture condition compared to the control condition, while the Joystick rotation condition wasn't significantly different from either of the other two conditions.
  3. For MR Reaction Time both the Gesture condition and the control condition showed significant gains on the Joystick rotation condition.
  4. Further analysis of the data revealed that (3) was explained by the pattern of improvement in females, while males tended to speed up similarly across all three conditions.
  5. The same pattern described in 3 and 4 held with transfer to the CMTT 
What's interesting here is that those children that didn't get any training on a task that ostensibly required Mental Rotation improved more than those that were required to physically rotate images.
Ping et al. suggest that what might be happening is that the children physically rotating the object might actually become dependent on this physical rotation while their "pure" MR performance suffers.

Their explanation makes a lot of sense - but I also think that it points to a potential problem in the MR literature. That is, while a lot of thought is given to the design of the experiments, especially the nature of the pre and post-tests, comparatively little thought is given to the nature of the training task. Superficial similarities between Mental Rotation and physically rotating pictures of animals with a joystick are all that seem to be required to justify using the latter as a training task for the former. The fact of the matter is that the computational (broadly construed) task is almost completely different in the two cases. In the one case there is an actual requirement for the subject to mentally rotate an image, in the other there is no mental rotation required at all. Where the two tasks are similar is actually at the point where the two images are compared to see if they are identical. This fact explains why we see improvement in accuracy in the Joystick condition but not in MR Reaction Time performance. The requirements in the Gesture conditions are much closer to the pre and post-tests in this case.

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