1. What is the sensation and how do psychologists study it? 2. What is the relationship between the nature of a physical stimulus and the types of sensory responses that originate from the stimulus? 3. What are the main senses and basic mechanisms that underlie its operation? 4. Why are we able to perceive the world in three dimensions, even though our retinas can only capture images in two dimensions? 5. How we develop auditory stimuli, paying attention to some and ignoring others.