Perception is influenced by perceptual set, context, motivation, and emotion. Perceptual set, or perceptual expectancy, refers to the tendency to perceive things in a particular way, influenced by previous experiences and expectations. This phenomenon affects the interpretation of stimuli, creating a set of mental tendencies and assumptions that impact sensory perceptions of sound, taste, touch, and sight.

An illustrative example of a perceptual set is the scenario where an airline pilot told the co-pilot to "cheer up" during takeoff. The co-pilot, expecting the usual command "gear up," mistakenly retracted the landing gear before the plane was off the ground. This demonstrates how expectations can shape interpretations of spoken words.

In one experiment, preschool children overwhelmingly preferred french fries served in a McDonald’s bag over those in a plain white bag, illustrating how expectations affect taste perception.

Stereotypes significantly color perceptions of people. For instance, individuals often perceive the same infant as bigger and stronger when named "Noah" compared to "Naomi." These stereotypes can be based on culture, ethnicity, gender identity, sexual orientation, income, age, or disabilities, and they alter how others are perceived and interpreted.

Immediate context influences perceptions by providing a framework for interpreting sensory information. For instance, drivers often view pedestrians' leisurely pace as obstructive, while pedestrians perceive drivers' impatience and speed as aggressive. This illustrates how context-specific roles and activities affect perceptual experiences.

Motivation impacts perception through physical tasks and mental load. A hill appears steeper when carrying a heavy backpack compared to being unburdened, demonstrating how physical effort influences visual perception. Similarly, a destination seems farther when feeling tired, as the anticipated effort alters the perceived distance.

Emotions influence perceptions by altering the interpretation of sensory inputs. Emotional states can bias perceptions in ways that align with the prevailing mood. For example, listening to sad music may lead to interpreting homophones like "mourning" instead of "morning," illustrating how emotions influence auditory perception.

Understanding how context, motivation, and emotions shape perception provides insights into the subjective nature of sensory experiences and highlights the interplay between mental and emotional states and the external world.

Emotions and motives also color social perceptions. For example, imagine two individuals experiencing the same mildly uncomfortable situation, such as a room that is slightly too cold. One person is generally well-rested and in a positive mood, while the other is sleep-deprived and already feeling irritable. The well-rested person might describe the room as "a bit chilly," but nothing too bothersome. However, the sleep-deprived individual, already in a heightened state of discomfort, might perceive the same cold temperature as being extremely uncomfortable or even unbearable. This tendency to perceive situations as more severe than they might objectively be is influenced by one's emotions and motives.

Emotional states can affect perceptions of conflict in relationships. Feeling loved and appreciated reduces the likelihood of viewing stressful events as threatening, often attributing such events to external factors like a bad day.