Within ACL 3, the concept of an imaginary straight line seems to organise the actions that are observed. The concept of a line guides what they do. The concept follows a developmental sequence seen in children under the age of three years old. The sequence is intentional grasp and release, moving an object back and forth, placing objects in a row, placing objects around the edge and outlining shapes, matching and sorting by colour and shape, and colouring or filling in the space in a shape or container.
Most of their actions are repetitive and done with grasp and pinch of their dominant hand. Their non-dominant hand may not be used much. With a cognitive disability, their procedural memories are accessible and habitual actions are done automatically.