An aluminum can of a soft drink is placed in a freezer. Later, you find that the can is split open and its contents frozen. Work was done on the can in splitting it open. Where did the energy for this work come from?
Module #18-‐ Basic concepts of sensation and perception Sunday, February 28, 2016 5:55 PM - Heather Sellersc 'urious mix of "perfect vision" and face blindness: the distinction between sensation and perception ○ Sensation: the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment (sensory receptors detect information→nervous system transmits the information to her brain) [normal] ○ Perception: the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events [almost normal] ○ Bottom -‐up processing: analysis that begins with the sensory receptors and works up to the brain's integration of sensory information [build up from smallest pieces of sensory info/detect lines, angels, colors…] ○ Top-‐down processing: constructs perceptions from the sensory input by drawing on our experience and expectations [perception that's driven by perception/ the brain applies what you know/expected -‐-‐ perception by content/your brain add meanings] - Transduction: the process of converting one form of energy into another that our brain can use § Eg. In sensation, the transforming of stimulus energies (sights, sounds, smells…) into neural impulses our brain can interpret ○ Three basic steps to all our sensory systems § Receive sensory stimulation (specialized receptor cells) § Transform that stimulation into neural impulses § Deliver the neural information to our brain ○ Psychophysics: studies the relationships between the physical energy we can detect and its effects on our psychological experiences - Thresholds ○ Absolute thresholds: the minimum stimulus energy needed to detect a particular stimulus (eg. Light, sound, pressure, taste…) 50% of the time [the point where sth. Becomes noticeable to our sense-‐s-‐-‐anything less than this goes unnoticed] ○ For weak stimulus (or signal, such as hearing-‐test tone): signal detection theory § A theory predicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise) [no single absolute threshold and the detection depends partly on a person's experience, expectations, motivation, and alertness]/[why people respond differently to the same stimuli, and why the same person's reactions vary as circumstances change] ○ Subliminal: stimuli you cannot detect 50 percent of the time for conscious awareness (below your absolute threshold) ○ Priming: the activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or response § Much of our information processing occurs automatically, out of sight, off the radar screen of our conscious mind. ○ Difference thresholds (just noticeable difference: jnd): the minimum difference a person can detect between any two stimuli half the time [the stimulus becomes detectable to us, how do we recognize if the stimulus changes] § It can increase with the size of the stimulus § Weber's law (Ernst Weber): the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage(rather than a constant screen of our conscious mind. ○ Difference thresholds (just noticeable difference: jnd): the minimum difference a person can detect between any two stimuli half the time [the stimulus becomes detectable to us, how do we recognize if the stimulus changes] § It can increase with the size of the stimulus § Weber's law (Ernst Weber): the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage(rather than a constant amount) □ Ex. Lights: 8%, weights: 2%, tones: 0.3% - Subliminal Persuasion ○ Acknowledge/ influence people in certain way (powerful) - Sensory adaptation: diminished sensitivity as a consequence of constant stimulation ○ Benefit: freedom to focus on informative changes in our environment without being distracted by background chatter ○ We perceived the world not exactly as it is, but as it is useful for us to perceived it. ○ It allows us to focus on changing stimuli - Perceptual Set: a mental predisposition to perceive one thing and not another, affects (top-‐down) what we hear, taste, feel and see ○ What determine our perceptual set -‐the preexisting schemas (influence how we apply top-‐down processing to interpret ambiguous sensations) - Context Effects ○ The context creates an expectation that, top down, influences our perception - Motivation and Emotion ○ Influence perceptions (top-‐down) and color our social perceptions ○ Perceptual bias