Chapter 1 I II The Human Model a Detectors eyes ears skin receptors receptors in nose and mouth b The computer the brain c Paradox we still don t understand perception but perceiving is something that occurs almost effortlessly The Perceptual Process a Perception is the end result of a complex behind the scenes processes b Perceptual Process sequence of processes that work together to determine our experience of a reaction to stimuli in the environment c Four categories of the perceptual process i Stimulus what is out there in the environment what we actually pay attention to what stimulates our receptors 1 Environmental Stimulus all of the things in our environment that we can potentially perceive 2 Attended Stimulus when a certain stimuli becomes the center of one s attention the attended stimuli often changes as people shift their attention from one stimulus to another 3 Stimulus on the Receptors when focusing on a certain stimuli this creates an image of the stimuli on the receptors of the retina thus the stimulus is transformed into an image which can also be described as a representation of a stimulus ii Electricity everything we perceive is based on electrical signals in our nervous system 1 Transduction the transformation of one form of energy into another form of energy a Occurs in the nervous system when energy in the environment light energy mechanical pressure chemical energy is transformed into electrical energy b Ex when looking at a particular stimulus the pattern of light created on the retina is transformed into electrical signals in thousands of visual receptors 2 Transmission once an image of a stimulus has been transformed into electrical signals in the receptors these signals travel out of the eye and are transmitted to the brain 3 Neural Processing interactions between neurons that occur as electrical signals in the receptors are being transmitted to the brain the receiver a The signals that originate in the receptors travel through a maze of interconnected pathways between the receptors and the brain and within the brain In the nervous system the signal that reaches the brain is transformed so that although it represents the original stimulus it is usually very different from the original signal iii Experience and Action where the backstage activity of b transduction transmission and processing is transformed in things we are aware of perceiving recognizing and acting on objects 1 Perception conscious sensory experience that occurs when the electrical signals that represent the moth are transformed by one s brain into the experience of perceiving a stimulus 2 Recognition our ability to place an object in a category that gives it meaning perception and recognition are two separate processes a Visual Form Agnosia an inability to recognize objects this demonstrates that one can still have the ability to perceive an object but can lose the ability to recognize and then identify what the object may actually be 3 Action includes motor activities such as moving the head or eyes and locomoting through the environment a The fact that perception often leads to action means that perception is a continuously changing process b As people perceive many changes continue to iv Knowledge any information that the perceiver brings to a occur situation 1 This category can affect a number of steps in the perceptual process 2 Rat Man Demonstration shows how recently acquired knowledge can influence perception 3 Example of how knowledge acquired years ago can also influence the perceptual process the ability to categorize objects 4 Bottom Up Processing Data Based Processing processing that is based on incoming data incoming data always provide the starting point for perception a Essential for perception because the perceptual process usually begins with stimulation of the receptors 5 Top Down Processing Knowledge Based Processing processing that is based on knowledge a Not always involved in perception but often is b As stimuli becomes more complex the role of top down processing increases III How to Approach the Study of Perception a Goal of perceptual research to understand each of the steps in the perceptual process that lead to perception recognition and action b Perception has been studied using two approaches i Psychophysical Approach to Perception 1 Gustav Fechner 1860 1966 physicist Elements of Psychophysics 2 Psychophysics refers to the use of quantitative methods to measure relationships between stimuli physics and perception psycho 3 Focuses on the relationship between physical properties of stimuli and the perceptual responses to these stimuli 4 Psychophysics refers to any quantitative measurement of the relationship between stimuli and perception 5 Ex measuring the stimulus perception relationship by asking an observer to decide whether two very similar patches of color are the same or different ii Physiological Approach to Perception 1 Involves measuring the relationship between stimuli and physiological processes PH1 and between physiological processes and perception PH2 2 Most often studied by measuring electrical responses in 3 Measuring PH1 measuring how a neuron responds to the nervous system different colors 4 Measuring PH2 measuring the relationship between a person s brain activity and that person s perception of colors iii To truly understand perception we must use both approaches because each approach provides information about different aspects of the perceptual process c Cognitive Influences on Perception How knowledge memories and expectations that people bring to the situation influence their perceptions i Starting place for top down processing IV Measuring Perception a Possible perceptual responses to a stimulus i Description indicating characteristics of a stimulus 1 All of the people in the student section are wearing red 2 Phenomenological Method when a researcher asks a person to describe what he or she is perceiving or to indicate when a particular perception occurs 3 This is where the study of perception begins because these are the basic properties that we are seeking to explain ii Recognition when we categorize a stimulus by naming it 1 Method for measuring a stimulus is presented and the observer indicates what it is iii Detection becoming aware of a barely detectable aspect of a stimulus 1 Classical Psychophysical Methods quantitative methods originally used limits adjustment and constant stimuli for measuring the relationship between