Months 9-10

Aware of vertical space (fears heights) ¹⁴

Begins understanding and reacting to small commands (e.g., no-no or give it to me)^{14, 30}

Interested in details of objects^{14, 41}

Object permanence^{14, 41}

Looks for contents in a container⁴¹

Gets bored with repetition of same stimuli^{14, 41}

May recall events from previous day¹⁴

Can keep a series of ideas in mind¹⁴

Begins to show persistence (6-9 months)^{14, 95}

Reaches for toy behind self without using visual senses¹⁴

Sees objects as separate from one another¹⁴

Increasingly imitates behaviors of others including tool use^{14, 41}

Modifies actions through trial-and-error to achieve goal¹⁴

Begins to know and point to body parts¹⁴

Matches two blocks¹⁴

Responds with expectation to repetition of event^{41, 14}

Makes goal-directed actions⁴¹

Experiments with objects⁴¹

Manipulates more than one object at a time⁴¹

Persistent in search for desired object⁴¹

Begins to show humor and teases⁴¹

Performs different actions with toys, depending on their characteristics⁴¹

Sustains interest in play (attends to both toy and adult) ⁴¹

Dumps objects out of container⁴¹

Shows interest in fitting things together⁴¹

Combines two objects functionally⁴¹

Understands few object names⁴¹

Uses objects to complete tasks⁴¹