Final answer:
The first part of observing uses visual clues of colors, contrast, and depth to perceive and interpret the visual field effectively.
Step-by-step explanation:
The three types of visual clues used during the first part of observing are colors, contrast, and depth. Colors refer to the different hues that can be seen and can give information about the nature of objects, such as their composition or state. Contrast involves the comparison of light versus dark areas in a visual field and can help in distinguishing various features or details. Depth, which includes cues like near versus far, aids in perceiving the three-dimensional aspects of a scene.