Task 1 Flashcards
Sensation
Ability to detect a stimulus and to turn that detection into private experience, Bottom- Up process. Hearing a voice through a phone. Step 1-4
Perception
: Act of giving meaning and/or purpose to those detected sensations, Top- down process. Recognizing your friend´s voice through the phone
Perceptual Process
. These seven steps, plus “knowledge” inside the person’s head, summarize the major events that occur between the time a person looks at an environmental stimulus (the tree in this example) and perceives the tree, recognizes it, and takes action toward it
PP Step 1&2
Environmental Stimulus
all of the things in our environment we can potentially perceive; because far too much happening in environment, we scan environment and look for something that catches our interest, like a tree trough light reflection (principle of transformation- stimuli and responds created by stimuli are transformed, changed, between environmental stimulus and perception)
first transformation when light hits tree and reflects from tree to person´s eyes (nature of reflected light depends on properties of light, properties of tree like shape, and properties of atmosphere like dust, fog)
PP 1&2
Stimulus on receptors
: The stimulus that focuses our attention is transformed into an image of the stimulus by the retina. It is a representation of the stimulus light reaches eye and is transformed
1) by the eye´s optical system Cornea (front of eye)
2) Lenses (behind it)
3) Form a sharp image of tree on receptors of person´s retina (network of nerve cells, covers black of eye and contains receptors of vision) > principle of representation: everything person perceives not based on direct contact with stimuli but representations of stimuli that are formed on receptors and on activity in person´s nervous system
PP Step 3
Receptor Process
• Sensory receptors: cells specialized to respond environmental energy (each sensory system´s receptors specialized to respond to specific type of energy) visual receptors respond to light, auditory receptors to pressure changes in air, touch receptors to pressure transmitted through skin, smell, taste receptors to chemicals entering nose and mouth
PP Step 3
Transduction
Transformation of one form of energy into another form of energy- occurs in nervous system when energy in the environment (light energy mechanical pressure, chemical energy) is transformed to electrical energy
Visual receptors transform light energy into electrical energy (contain light- sensitive chemical visual pigment that reacts to light)
PP Step 3
Transmission
After stimulus has been transformed into electrical signals, these signals activate other neurons, which activate more neurons; eventually these signals reaches the brain
PP Step 4 Neural Processing
Transition occurstree represented by electrical signals in thousands of visual receptors
• Complex network of neurons
1) transmit signals from receptor through retina, to the brain, within the brain
2) changes (processes) signals (in receptors) travel through a maze of interconnected pathways between the receptors >neural processing
• The signal that reaches the brain is transformed so that it represents the original stimulus (it is usually very different from the original signal), it is a “new representation” of the stimulus
Electrical signals from each sense arrive at the primary receiving area for the sense in the cerebral cortex of the brain.
Vision most of the occipital lobe
Hearing part of the temporal lobe
Skin senses (touch, temperature, pain) parietal lobe
Signals from all senses Frontal lobe (important part in perception).
PP Step 5&7 Behavioral Responses -Perception -Recognition -Action
Perceiving, recognizing and acting on objects in the environment
Reflectionfocusingtransductiontransmissionprocessingbehavioral responses
• Perception: conscious sensory experience, awareness of the tree, occurs when the electrical signals that represent the stimulus are transformed by the brain into experience of seeing the stimulus, Top- down way
• Recognition: Ability to place an object in a category that gives a meaning like “tree” Visual form agnosia: when you can perceive an object but can´t recognize it as a whole
• Action: Includes motor activities (walk, climb the tree) or such as moving the head or eyes and locomoting through the environment
Knowledge
Any information that perceiver brings to situation, placed inside the person´s head in diagram; can affect number of the steps in perceptual process
Bottom Up
(data-based processing): Processing based on incoming data. You do not know that fire burns, so you get too close and suddenly knows that it burns
Top- Down Processing
(knowledge- based processing) Processing based on knowledge. As stimuli becomes more complex the role of top- down processing increases. Knowledge is not always involved in perception but often is sometimes without being aware of it. You know fire is hot, so you do not get too close to it
Interaction between Bottum Up and Top Down
top-down: pharmacist reads unreadable scribble on doctor’s prescription. She starts with the patterns that the doctor’s handwriting creates on her retina. Once these bottom-up data have triggered the sequence of steps of the perceptual process, top-down processing can come into play as well. For example, the pharmacist uses her knowledge of the names of drugs, past experience with doctor’s writing, understand the unreadable squiggles on the prescription
Measuring Perception
Absolute Threshold (Fechner)
-Oblique effect
measuring the threshold for detecting gratings of different orientations threshold is lower (finer lines can be detected) when the gratings are horizontal or vertical rather than slanted or oblique
