SENSATION AND PERCEPTION KEY TERMS
BOTTOM-UP PROCESSING • BOTTOM-UP PROCESSING refers to processing sensory information as it is coming in. • In other words, if I flash a random picture on the screen, your eyes detect the features, your brain pieces it together, and you perceive a picture. What you see is based only on the sensory information coming in. • Bottom-up refers to the way it is built up from the smallest pieces of sensory information.
TOP-DOWN PROCESSING • TOP-DOWN PROCESSING, on the other hand, refers to perception that is driven by cognition. Your brain applies what it knows and what it expects to perceive and fills in the blanks, so to speak. • Look at the shape in the box to the right. Seen alone, your brain engages in bottom-up processing. There are two thick vertical lines and three thin horizontal lines. There is no context to give it a specific meaning, so there is no top-down processing involved.
TOP-DOWN PROCESSING • Now, look at the same shape in two different contexts. Surrounded by sequential letters, your brain expects the shape to be a letter and to complete the sequence. In that context, you perceive the lines to form the shape of the letter “B. ” Surrounded by numbers, the same shape now looks like the number “ 13. ” When given a context, your perception is driven by your cognitive expectations. Now you are processing the shape in a topdown fashion.
SELECTIVE ATTENTION • 11, 000 bits of information per second • Consciously process about 40 • Cocktail Party Effect • Your ability to attend to only one voice among many
INATTENTIONAL BLINDNESS • Inattentional blindness, also known as perceptual blindness, is a psychological lack of attention that is not associated with any vision defects or deficits.
CHANGE BLINDNESS • Change blindness is a perceptual phenomenon that occurs when a change in a visual stimulus is introduced and the observer does notice it.
POP-OUT EFFECT • The pop-out effect (also known as pop-out phenomenon) occurs when a visual stimulus that is comprised of differing components has mostly similar looking objects but one differing object that 'pops-out' or stands out very noticeably from the other objects in the visual field. When looking at a visual field a unique stimulus can be located much faster than stimuli that is similar.
TRANSDUCTION • Conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brain can interpret.
ABSOLUTE THRESHOLD • The term absolute threshold is often used in neuroscience and experimental research. An absolute threshold is the smallest detectable level of a stimulus. For example, in an experiment on sound detention, researchers may present a sound with varying levels of volume. The smallest level that a participant is able to hear is the absolute threshold. • However, it is important to note that at such low levels, participants may only detect the stimulus part of the time. • Because of this, the absolute threshold is usually defined as the smallest level of a stimulus that a person is able to detect 50 percent of the time.
SIGNAL DETECTION THEORY • Predicts when we will detect weak signals (measured as our ratio of “hits” to “false alarms”) • Your ability or likelihood to detect some stimulus is affected by the intensity of the stimulus (e. g. , how loud a noise is) and your physical and psychological state (e. g. , how alert you are). • For example, when you walk to your car that is parked in an empty parking lot late at night all by yourself, you might be much more aware of noises because the situation is somewhat threatening (you are primed and listening carefully to hear anything and everything). In this case, you may hear some slight noises that you might otherwise not hear if you were in a different situation that was not as threatening. Thus, your ability to detect signals or noises has been affected by these factors.
SUBLIMINAL • When we are presented with some information that is just below our conscious awareness but still reaches our brains, it is a subliminal message - meaning, the information is getting into our systems and to our brains without us truly being aware of it.
JUST NOTICEABLE DIFFERENCE THRESHOLD • The absolute threshold should not be confused with the difference threshold, which is the smallest possible detectable difference between two stimuli.
PERCEPTUAL SET • Perceptual set is a tendency to perceive or notice some aspects of the available sensory data and ignore others. • This is the expectation of a person to see or perceive something based on prior experience. • Stereotypes are an example of perceptual set
CONTEXT EFFECTS • The Context Effect is a part of Cognitive Psychology that states that the context (environmental factors) that surrounds an event affects how an event is perceived and remembered. • This effect, that is largely used in the science of marketing, holds that an event is more favorably perceived and remembered when the surrounding environment is comfortable and appealing.
EMOTION AND MOTIVATION • In addition to context, emotion and motivation can also create expectations and color our interpretation of events and behaviors.
SENSORY ADAPTATION • We get used to everything. One reason we get used to everything is because of reduced sensitivity to stimulation that results from repeated presentations of that stimulation. • Does not apply to our eyes that are constantly moving. • Allows us to focus on informative changes in our environment