PSYCH_2006 Lecture Foundations of Perception and Cognition PDF

Foundations of Perception and Cognition Introduction to Sensation Perception Dr Deanne Green  We acknowledge and pay our respects to the Kaurna people, the traditional custodians whose ancestral lands we gather on. We acknowledge the deep feelings of attachment and relationship of the Kaur...

Foundations of Perception and Cognition Introduction to Sensation Perception Dr Deanne Green  We acknowledge and pay our respects to the Kaurna people, the traditional custodians whose ancestral lands we gather on. We acknowledge the deep feelings of attachment and relationship of the Kaurna people to country and we respect and value their past, present and ongoing connection to the land and cultural beliefs. Contact details Consultation time: by appointment Office: Hughes 517 I have an open-door policy – but I am not always in my office Email: [email protected] Perception Lectures What will you learn 1. Intro to sensation and perception 2. Methods 3. Spatial vision 4. Body senses 5. Depth perception 6. Motion perception Intro to Sensation and Perception Part 1 Definition What are Sensation Examples and Perception? Psychological relevance Sensation Sensation ¹ perception Sensation Sensation Sensation ¹ perception Sensory processing (the brain) alters perception Sensation = the information sent to the brain by our senses Perception Sensation ¹ perception Sensory processing (the brain) alters perception Perception = our awareness of our environment Perception Sensation Stimuli Perception Awareness Stimuli Organism’s response Relevance to psychology Perception is the foundation for everything else: memory, learning, motor skills, emotion, motivation, social psychology, personality and pathology. Visual memory example Passive Active Stimuli Attention Attention Encoding Retrieval Two different worlds Physical world: sensory input Perceptual world: our brain’s interpretation of that input Example Video Anyone remember this meme? Sensations Part 2 Input Processing Sensation Examples: visual sensation Classification of the senses Sense Sensation Receptor Sensory Cortex Structure Vision Electromagnetic Photoreceptors Eyes Primary energy Visual cortex Primary Visual Cortex Classification of the senses Sense Sensation Receptor Sensory Cortex Structure Vision Electromagnetic Photoreceptors Eyes Primary Visual energy Cortex Hearing Air pressure Mechanoreceptors Ears Auditory Cortex waves Auditory Cortex Auditory cortex Classification of the senses Sense Sensation Receptor Sensory Cortex Structure Vision Electromagnetic Photoreceptors Eyes Primary Visual energy Cortex Hearing Air pressure Mechanoreceptors Ears Auditory Cortex waves Touch Tissue distortion Mechanoreceptors Skin, Somatosensory Thermoreceptors Muscle Cortex Somatosensory Cortex Classification of the senses Sense Sensation Receptor Sensory Cortex Structure Vision Electromagnetic Photoreceptors Eyes Primary Visual energy Cortex Hearing Air pressure Mechanoreceptors Ears Auditory Cortex waves Touch Tissue distortion Mechanoreceptors Skin, Muscle Somatosensory Thermoreceptors Cortex Taste/Smell Chemical Chemoreceptors Nose/Mouth Taste and Olfactory Cortex Taste and Olfactory Cortex Gustatory (taste) cortex Olfactory cortex Classification of the senses Sense Sensation Receptor Sensory Cortex Structure Vision Electromagnetic Photoreceptors Eyes Primary Visual energy Cortex Hearing Air pressure Mechanoreceptors Ears Auditory Cortex waves Touch Tissue distortion Mechanoreceptors Skin, Muscle Somatosensory Thermoreceptors Cortex Taste/Smell Chemical Chemoreceptors Nose/Mouth Taste and Olfactory Cortex Balance Mechanoreceptors Vestibular Temporal Cortex organs Temporal cortex Cerebellum A closer look at Vision Part 3 Vision The retina Kolb, 2011 Distribution of rods and cones Wadsworth, 2002 The visual pathway The visual pathway What do we see? The world appears high resolution across the visual field What do we see? The world appears high resolution across the visual field In reality, visual resolution varies across the visual field Measuring Perception Part 4 Measurement properties Measurement methods Measuring Perception Examples Measuring Perception If perception is merely internal, can it be measured? Should it be measured? Our approach: if we can determine how perception changes under various conditions, then we should be able to predict these changes and therefore understand perception. Measurement Properties Measuring perception is known as Psychophysics, pioneered by Gustav Fecner (1800s) Threshold – below threshold, we don’t sense it Absolute Threshold - the minimum amount of energy needed to detect a stimulus Classical idea: there is a sharp transition in the internal state of the observer between when a stimulus can and cannot be detected.  Methods Classical idea: Steep transition Detected 100 Detected 90 80 of Stimuli 70 60 of Stimuli 50 40 Percent 30 Percent 20 10 0 9 10 11Stimulus 12 Intensity 13 14 15 16 17 Stimulus Intensity  Methods Current understanding (psychometric function) 100! Percent of Stimuli Detected 80! 60! 50 40! 20! 0! 140! 150! 160! 170! 180! 190! 200! 210! Stimulus Intensity Measurement Methods Psychophysical methods (Fechner, 1860) 1. Method of Adjustment: The observer adjusts intensity until they can just barely detect the stimulus 2. Method of Limits: The experimenter adjusts intensity up (or down) until the observer changes their response 3. Method of Constant Stimuli: The observer views several preset stimulus intensities (in random order) and judges whether each is perceived or not  Methods Probabilistic function 100! Percent of Stimuli Detected 80! 60! 40! 20! 0! 140! 150! 160! 170! 180! 190! 200! 210! Stimulus Intensity  Methods Threshold example Psychophysical function 25! 20! Threshold 15! 10! 5! 0! 400! 450! 500! 550! 600! 650! Wavelength of Light (nm)  Methods Threshold example 0.14! Sensitivity function 0.12! 0.1! Sensitivity 0.08! 0.06! 0.04! 0.02! 400! 450! 500! 550! 600! 650! Wavelength of Light (nm)  Methods Threshold example Sensitivity function 1. Psychophysical Function 2. Sensitivity Function 3. Just Noticeable Difference the minimum change in a stimulus for the change to be perceivable Using measurements Part 5 Examples: Colour vision Using Measurements Colour blindness Human colour vision starts with cones in the retina Densely packed in the fovea Most sensitive to 560nm, daylight levels Three different types of absorption spectra for cones: Ø Short wavelengths Ø Medium wavelengths Ø Long wavelengths Human colour wavelengths Human colour Sensitivity Colour perception varies across species Humans: daylight Cats: crepuscular Possums: nocturnal Dogs: may have hunted at night Colour Vision Deficiency More common in men than women Two most common types are Deuteranopes (complete lack of green (medium wave) cones) Protanopes (complete lack of red (long wave) cones)  Color Vision This is an Ishihara colour This is an Ishihara plate This is what a red/green plate used to test for commonly used to check for color-blind person might see. colour blindness red/green color blindness  Color Vision This This isisan Thisis an Ishihara anIshihara plate Ishiharaplate colour This This isiswhat Thisis what a red/green how a red/green red-green commonly commonly used plate usedused to for to to test check for check for color-blind color-blind person person colour-blind personmight see. might see. red/green red/green color blindness color colour blindness blindness would see the plate Why is this important Knowing that people perceive the world differently than what they sense helps us to adjust the world to help E.g., traffic lights Summary Sensation ¹ perception Perception is a product of processing of sensory information Psychophysical techniques can be used to measure perception An understanding of sensory and perception can tell us about psychological factors