Sensation and Perception psyc 320 Takashi Yamauchi © Takashi Yamauchi (Dept. of Psychology, Texas A&M University) Ch 1

Sensation & Perception Ch. 1: Introduction to perception Main topics Perceptual processes How to study perception How to measure perception Ch 1

Sensation & Perception How is this course different from other psychology courses? learn sensation & perception Some very basic form of mind (sensing & perceiving) Deal with fundamental principles of psychology Ch 1

Questions: What is perception? Perception is about perceiving. What is perceiving? What do we do when we perceive? We see, smell, hear, feel, taste, … Ch 1

What tools do we have for perceiving? Eyes, ears, nose, tongue, skin, eyes  see, ears  hear, nose  smell, tongue  taste, skin  feel (temperature) skin  feel (touch) Ch 1

What do eyes, a nose, ears, a tongue, and skin do? Ch 1

What does the eye do? Eye: Seeing, yes but what is seeing? detecting light What is light? electromagnetic energy Ch 1

What is electromagnetic energy? Electro + magnetic + energy = electromagnetic energy Electromagnetic energy is a stream of photons. www.wikipedia.org Ch 1

What are photons? They are massless particles each traveling in a wave-like pattern and moving at the speed of light. The smallest (quantum) unit of light/electromagnetic energy. It is the carrier of electromagnetic radiation of all wavelengths such as gamma rays, X-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves. Ch 1

So what is “seeing”? Detecting some form of the movement of photons (electromagnetic radiation). Ch 1

What does the ear do? Hears sound What is sound? the vibration of air. What is the vibration of air? Where do they come from? Air moves when something else moves Ch 1

What does the nose do? Nose: Where does smelling come from? is for smelling Where does smelling come from? Smelling is a “sensation caused by odorant molecules dissolved in air.” (wikipedia.org) Ch 1

Odorant molecules? What are they? Odorant (aroma compound)  chemical compound (e.g., H2O; a chemical substance of two or more different chemical elements.) Where do they come from? Organic compounds  foods, flowers, Inorganic compounds  ammonia,… Ch 1

Taste How do we get that? Where do we get that? From our tongues. From foods we eat. From specific chemicals. Ch 1

What does the skin do? Detect temperature: What is temperature? It is about how hot or cold something is. How does something get hot or cold? Temperature is the result of the motion of particles which make up a substance. Temperature increases as the energy of this motion increases. (wikipedia) Ch 1

What does the skin do? feels touching  It responds to mechanical stimulation or pressure Ch 1

So, what is perception? Perception is a system that tells us about an environment. Ch 1

Eye, ear, nose, tongue & skin They are sensors. They are detecting some kind of changes in an environment. Ch 1

So, studying perception we need to study How the eye works, How the ear works, How the nose works, How the tongue works, and How the skin works Is that all? Ch 1

What tools do we have for perceiving? Eyes, ears, nose, tongue, skin, Eyes  see, ears  hear, nose  smell, tongue  taste, skin  feel Are these all? NO!  Brain (not Bryan) Ch 1

The brain is the locus of perception the study of perception entails the study of the brain and behavior. Ch 1

A quick demonstration Tell me what you see. Ch 1

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(A) (B) (A) (B) Ch 1

Visual Illusions Why does this happen? Tell me what these illusions teach us. Ch 1

What is perception? Perception involves: Perception is about Detecting the information in the environment. Sending the information to the brain, and interpreting it. Perception is about Detecting and interpreting Ch 1

Let’s have some break. Listen to music See a painting Ch 1

Paul Klee: Golden fish Ch 1

Paul Klee: Ad Parnassum Ch 1

Anselm Kiefer: Nuremberg Ch 1 Anselm Kiefer: Nuremberg

Henri Rousseau: The Dream Ch 1

What’s going on? Perception is about detecting, but also more than detecting. Ch 1

What’s going on when we see the pictures? When we listen to beautiful music, we often see a picture. When we see a beautiful picture, we hear music. How come? Ch 1

How come? Different types of physical information (air vibration, light energy) are translated into a common language in the brain  neural information Environmental Stimuli (e.g., light energy) Transduction Neural Processing Perception Ch 1

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Key points: Perception is about finding out what is going on in an environment. Perceptual organs (eyes, ears, nose, skin, a tongue) are basically detectors (sensors) Perception requires transforming physical information (e.g., light) into neural information. Perception also involves “interpretation,” which is carried out by the brain. Ch 1

Studying perception How perceptual detectors work. How physical information is transformed (e.g., light) into neural information. How neural information is processed in the brain. How neural information is interpreted and triggers a specific form of perception. Ch 1

How come? Different types of physical information (air vibration, light energy) are transformed into a common neural language in the brain  neural information Environmental Stimuli (e.g., light energy) Transduction Neural Processing Perception Ch 1

Demonstration (attention & perception) An interaction between attention and perception cognition and perception Tell me what you see. Ch 1

Tired Old Sick Dark Slow Heavy Hospital ugly death Ch 1

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Beautiful Young Fresh Fast Energy Juicy Clean cheerful Vigorous

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Demonstration (knowledge and perception) Ch 1

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What did you see? What does this tell? Ch 1

Perceptual process Perception is the end result of complex processes. Ch 1

Why study perception? If the doors of perception were to be cleaned, man would see everything as it truly is…..Infinite. William Blake Ch 1

How to approach the study of perception Levels of analysis Psychophysical level of analysis Physiological level of analysis Ch 1

Measuring Perception Psychophysical level of analysis Description Phenomenological method E.g., Let a person describe what they see Recognition Detection Ch 1

Detection Absolute threshold is the smallest amount of stimulus energy necessary to detect a stimulus. E.g., eye exam Difference threshold is the smallest difference between two stimuli that a person can detect. Ch 1

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Demonstration Ch 1

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Demonstration: Measuring weight DL (difference threshold) gets larger as the standard stimulus gets larger. Ch 1

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Demonstration Color, line, length Ch 1

The impact of standard stimuli DL (difference threshold) gets larger as the standard stimulus gets larger. Weber’s law DL/S=K DL: difference threshold S: standard stimulus K: constant Ch 1

Weber’s law Ch 1

Question: With a standard stimulus 1 kg, John’s difference threshold was 0.25kg. With a standard stimulus 10kg, what would be John’s difference threshold? Ch 1

Question: With a standard stimulus 1 kg, John’s difference threshold was 0.25kg. With a standard stimulus 10kg, what would be John’s difference threshold? DL/S=K DL: 0.25 S: 1 K: 0.25 DL/S=K DL: ? S: 10 K: Ch 1

Magnitude estimation Assign a value to a standard stimulus The subject estimates the value of a target stimulus. Ch 1

Magnitude estimation Standard: == 10 Target: == ? Standard: == 100 Ch 1

Standard: == 100 Target: == ? Ch 1

Standard: == 100 Target: == ? Ch 1

Steven’s power law S is the physical magnitude of a target that you are estimating. P is your estimation K is some value (constant) n is some value Ch 1

Magnitude estimation Ch 1

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Steven’s power law S is the physical magnitude of a target that you are estimating. P is your estimation K is some value (constant) n is some value Ch 1

Experiment (you are estimating the length of lines) Ch 1

Target = ? Standard = 100 Ch 1

K: some value (constant) = 21.5 P = S raised to the n-th power P: your estimation S: stimulus intensity n: some value =0.33 K: some value (constant) = 21.5 P = S raised to the n-th power Ch 1

Experiment (you are estimating the intensity of electric shock) Standard = 100 Target = ? Ch 1

K: some value (constant) = 0.1 P: your estimation S: stimulus intensity n: some value =1.5 K: some value (constant) = 0.1 Ch 1

Estimating electric shock Estimating the length of lines Ch 1

Steven’s power law S is the physical magnitude of a target that you are estimating. P is your estimation K is some value (constant) n is some value Ch 1

Threshold Absolute threshold Difference threshold Ch 1

Difference threshold Weber’s law Stevens’s law Ch 1