PSY280 Midterm 1 Study Sheet

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Matthias Niemeier

Lecture 1: Introduction Philosophers & Scientists 1. Heraclitus: You can never step into the same river twice - The idea that perceiver cannot perceive the same event in exactly the same manner each time 2. Democritus: The world is made up of atoms that collide with one another - Sensations are cause by atoms leaving objects and making contact with our sense organs 3. Plato: Truest sense of reality comes from peoples minds and souls 4. Descartes: Dualist view; mind and body existing 5. Hobbes: Believed that everything that could ever be known or even imagined had to be learned through the senses 6. Locke: Sought to explain how all thoughts, even complex ones, could be constructed from experience with a collection of sensations 7. Fechner: Invented psychophysics and true founder of experimental psychology 8. Weber: Discovered that the smallest change in a stimulus is a constant proportion of the stimulus level 9. Helmholtz: Studied activity of neurons and how fast they transmit signals (slow speed of nerves contradicts vitalism) wanted brain and behaviour to obey physical laws Perception: The result of the physical interactions between the world and our bodies Nativism: The idea that the mind produces ideas that are not derived from external sources Vitalism: Belief that special vital forces drive living organisms Empiricism: The idea that experience from the sense is the only source of knowledge Adaptation: A reduction in response caused by prior continuing stimulation Sensory transducer: A receptor that converts physical energy from the environment into neural activity Mind-body dualism: The idea positing the existence of two distinct principles of being in the universe spirit/soul and matter/body Monism: The idea that the mind and matter are formed from, or reducible to, a single ultimate substance or principle of being (i.e. Empedocles ;) ) Materialism: The idea that physical matter is the only reality, and everything including the mind can be explained in terms of matter and physical phenomena. Psychophysics Panpsychism: The idea that all matter has consciousness (Fechner) Psychophysics: The science of defining quantitative relationships between physical and psychological events Psychophysical Methods 1. Fechners Method of Constant Stimuli: Stimuli ranging in intensities (from rarely to always perceivable) are presented to participant they respond based on this (i.e. Y/N) Basically: You are gradually able to detect the stimuli there is no sharp moment going from never detecting it to always detecting it 2. Fechners Method of Limits: A particular dimension of a stimulus or the difference between two stimuli is varied incrementally until the participant responds differently (Staircase method: presenting a stimuli until it can no longer be detected; presenting a stimuli until it can first be detected) 3. Fechners Method of Adjustment: The subject controls the change in the stimulus 4. Magnitude Estimation: Participants are asked to assign values according to perceived magnitudes of stimuli 5. Cross-Modality Matching: Matching intensities/magnitudes of sensations coming from different modalities (i.e. adjusting brightness of a light to correspond to loudness of a tone) Theories Signal detection theory: A psychophysical theory that quantifies the response of an observer to the presentation of a signal in the presence of noise - There is always internal noise -- a static in your nervous system. If you are in the quitest of places, you still hear something; if you close your eyes in darkness, you still see something. - Helps us understand what's going on when we make decisions under conditions of uncertainty Laws Fechners Law - Describes relationship between stimulus magnitude and sensation magnitude - Sensation magnitude increases to log of stimulus intensity (arc shape) Exception: electric shock where a small change causes greater change in the intensity - The greater the stimulus intensity, the more change in the sensation intensity affects it - Assumes that JNDs are perceptually equivalent Stevens Power Law - Describes relationship between stimulus magnitude and sensation magnitude - Sensation magnitude is proportional to stimulus magnitude raised to an exponent JND (Just Noticeable Difference)/Difference Threshold: Smallest detectable difference between two stimuli (one of which is a reference stimuli) Two-point Threshold: Minimum distance at which two stimuli can be distinguished Absolute Threshold: Minimum amount of stimulation necessary for a person to detect a stimulus 50% of the time Theories Signal Detection Theory: Quantifies response of an observer to a signal in the presence of noise - Helps us understand how we make decisions under uncertainty - Measured by criterion (i.e. stimulus is there/not) and sensitivity (ease in which participant can tell detect stimuli) Receiver Operating Characteristic Curve (ROC): The hit rate as a function of the false-alarm rate. - If diagonal, the participant cannot distinguish (hit & false alarm the same) - The higher the curve bows upward, the greater chance they have of guessing correctly. Doctrine of specific nerve energies (Muller): We are aware of only the activity in our nerves, and we cannot be directly aware of the world itself (i.e. we experience vision because the optic nerve leading from the eye to the brain is stimulated - but it does not matter if light actually stimulated the nerve) these sensations are perceived by the Cranial Nerves. Hodgkin-Huxley Cycle: Electrochemical process involving Na+ (in) & Ka+ (out) ions moving out of neuron (action potential near cell body -> propagates down axon towards axon terminal) neurotransmitters work together to transmit and process information Neuron Activity Electroencephalography (EEG): A technique using many electrodes on the scalp to measure electrical activity from populations of many neurons in the brain. Averaged into event-related potentials. - Does not specify the brain location Magnetoencephalography (MEG): Measures changes in magnetic activity across populations of many neurons in the brain Neuroimaging Methods Computed Tomography (CT): Uses X-rays to create images of slices through volumes of material Magnetic Resonance Imaging (MRI): Uses the response of atoms to strong magnetic fields to form images of structures (i.e. the brain) Functional Magnetic Resonance Imaging (fMRI): Measures localized patterns of activity in the brain through BOLD signals. Activated neurons provoke increased blood flow - this is then quantified (change is measured in response to the strong magnetic field) Blood oxygen level-dependent signal (BOLD): Since an active brain demands more blood, this is measured in order to pick up evidence of the demand for more resources. However, it takes a few seconds for the BOLD signal to be apparent (unlike EEG or ERP methods) Positron emission tomography (PET): Imaging technology that defines neuron activity in areas of the brain by measuring the metabolism of brain cells using safe radioactive isotopes Lecture 2: Olfaction, Taste, & Vestibular System i) Olfaction Odors: The translation of a chemical stimulus into a smell sensation. Olfactory sensations - the stimuli for these chemical compounds are odorants which must be the following in order to be sensed: 1. Volatile (be able to float through air) 2. Small 3. Hydrophobic (repellent to water) The human olfactory apparatus: - Nasal cycle - what you want is air flow in different speeds because different scents are perceived better based on this (ridges, olfactory cleft, olfactory epithelium) - Sniffing - one way to enhance your ability to smell something - enhances air flow and makes you more sensitive. However, the scent itself remains the same - we can just detect it better. - Smelling is just a secondary purpose (the first of course is to allow us to breathe) Olfactory Physiology Sequence of Events (Olfaction): - Air travels through olfactory cleft and reaches olfactory epithelium - Odorants in the air react with the olfactory receptors in the cilia of the olfactory sensory neurons located in the epithelium - Action potential is transmitted through the axon of the OSN (to the olfactory nerve), cribiform plate (a sieve), and finally to the olfactory bulb The olfactory cleft: A narrow space where air flows and where the olfactory epithelium is located The olfactory epithelium (the "retina" of the nose): - Yellowish patch of mucous membrane - Purpose: to detect odorants in inhaled air - Located on both sides of the upper portion of nasal cavity & olfactory cleft Cells within Olfactory Epithelium - Supporting cells: provides metabolic and physical support for the OSNs - Basal cells: precursor cells to OSNs (will become olfactory sensory neurons later) - Olfactory sensory neurons (OSNs) Olfactory sensory neurons (OSNs) - Have cilia sticking out into mucus part of the epithelium (snot) - Cilia/cilium: The receptor sites for odorant molecules are located in the cilia - the first structures involved in olfactory signal transduction - Olfactory receptors are used to sense odor. They react with odorants and detect action potential to travel through OSN - they are located on the cilia. There are ~1000 receptor genes, each of which code for a single type of OR. There are also pseudo- genes (dormant and dont produce proteins) Anosmia: Inability to smell permanently due to lesions to olfactory nerve (thin axons) (i.e. through head trauma, infections). Can lose sense of taste/flavor and sense of danger/warning also an early symptom of Alzheimers/Parkinsons The Olfactory Bulb: - Where action potential is transferred to (from the OSN) - Sends infor
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