Images of the pieces when they are flat may be retained in working memory while their position in actual space is moved or the shape is altered. The assumption is that the shape of the piece stays the same. Their comparisons and evaluations include:
- Consideration of the effects on three dimensional objects.
- Bilateral coordination to rotate objects while causing effects.
- Consideration of modified actions to make causing effects easier.
Before starting, the person may form an image of what the situation looked like and compare that to the effects they produce later. During assembly, the parts are often installed together in a pre-determined arrangement that suits an identified purpose. The spatial fit is evaluated during assembly by comparing before and after fits. To make the comparison, the before information has to be retained for a few minutes. Another comparison may be made by looking at what they have done and comparing it to a personal image, or diagrams and pictures.
The process of evaluating while doing the activity is similar for taking things apart, adjusting to volume or changing consistency.