Chapter 3 Notes

Chapter 3 Notes - Chapter 3: Sensation and Perception...

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Chapter 3: Sensation and Perception Sensing and Perceiving the World o Sense - a system that translates data from outside the nervous system into neural activity o Sensations - raw information (messages) from the senses Sensations provide the vital link between the self and the outside world o Perception - the process through which people take raw sensations from the environment and give them meaning, using knowledge, experience, and understanding of the world Perceptions influence your thoughts, feelings, and actions o Something must first be sensed then perceived Sensory systems o Senses gather information about the world by detecting various forms of energy, such as light (eyes), sound (ears), and physical pressure (skin) o Humans depend mainly on vision, hearing, and the skin senses to gain information about the world o All of the senses must detect information about stimuli, encode it into neural activity, and then send this encoded information to the brain o First step: involves accessory structures - structures that modify a stimulus o Second step: transduction - process of converting incoming physical energy into neural activity Transduction takes place in neural receptors - cell that are specialized to detect certain types of energy and convert it into neural activity These receptors respond to incoming energy by firing an action potential and releasing neurotransmitters that send signals to neighbor cells Sensory adaptation -decreasing responsiveness to an unchanging stimulus o Third step: sensory nerves carry information from receptors to the brain For all senses except smell the information goes to the thalamus o Fourth step: the thalamus does some initial processing of the information o Fifth step: thalamus sends it to the cerebral cortex o Encoding Senses When receptors encode the energy that is brought in, it allows you to make sense of the stimulus Encoding - translation of the physical properties of a stimulus into specific pattern o Absolute Thresholds The minimal detectable amount of light, sound, pressure, or other physical energy is called the absolute threshold
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Psychologists discovered the absolute thresholds by exploring psychophysics , the relationship between psychical energy and the psychological experience of that energy Absolute threshold is an all-or-nothing response Absolute threshold - redefined as the minimum amount of stimulus energy that can be detected 50% of the time The “absolute” threshold varies because of internal noise and our response bias Internal noise - the spontaneous random firing of nerve cells that occurs because the nervous system is always active o If the amount of internal noise happens to be high at a particular moment, your sensory systems might mistakenly interpret the noise as an external stimulus Response bias (response criterion) - the internal rule a person uses to decide whether or not to report a stimulus o A person’s motivation
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Chapter 3 Notes - Chapter 3: Sensation and Perception...

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