The postural differences between ACL 4.4 and 4.6 occurs as the improvement in mental energy results in the person sitting upright, picking up their head and scanning the environment. This results in a behavior which is easy to identify.
The ability to store an image in the person's working memory which lasts for a few seconds also enters the scale in ACL 4.6. This results in the ability to keep comparing to a sample and keep an image even when it is partially hidden. The study groups had a lot of fun with the picture of the tractor which had tires placed over the body of the tractor. When the person was functioning below ACL 4.6, the tractor body floated over the tires.
The ability to hold an image in their working memory also results in the person only needing to refer to the sample per action. Within ACL 4.6, the comparisons occur until the person becomes fatigued. The comparison to the sample then stops and mistakes occur.