5.1 Sensation versus Perception - Psychology 2e | OpenStax.pdf

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Learning ObjectivesBy the end of this section, you will be able to:Distinguish between sensation and perceptionDescribe the concepts of absolute threshold and difference thresholdDiscuss the roles attention, motivation, and sensory adaptation play in perceptionSensationWhat does it mean to sense something? Sensory receptors are specialized neurons thatrespond to specific types of stimuli. When sensory information is detected by a sensoryreceptor,sensationhas occurred. For example, light that enters the eye causes chemicalchanges in cells that line the back of the eye. These cells relay messages, in the form ofaction potentials (as you learned when studying biopsychology), to the central nervoussystem. The conversion from sensory stimulus energy to action potential is known astransduction.You have probably known since elementary school that we have five senses: vision, hearing(audition), smell (olfaction), taste (gustation), and touch (somatosensation). It turns out thatthis notion of five senses is oversimplified. We also have sensory systems that provideinformation about balance (the vestibular sense), body position and movement(proprioception and kinesthesia), pain (nociception), and temperature (thermoception).The sensitivity of a given sensory system to the relevant stimuli can be expressed as anabsolute threshold.Absolute thresholdrefers to the minimum amount of stimulus energythat must be present for the stimulus to be detected 50% of the time. Another way to thinkabout this is by asking how dim can a light be or how soft can a sound be and still bedetected half of the time. The sensitivity of our sensory receptors can be quite amazing. Ithas been estimated that on a clear night, the most sensitive sensory cells in the back of theeye can detect a candle flame 30 miles away (Okawa & Sampath, 2007). Under quietconditions, the hair cells (the receptor cells of the inner ear) can detect the tick of a clock 20feet away (Galanter, 1962).It is also possible for us to get messages that are presented below the threshold forconscious awareness—these are calledsubliminal messages. A stimulus reaches aphysiological threshold when it is strong enough to excite sensory receptors and sendnerve impulses to the brain: This is an absolute threshold. A message below that thresholdis said to be subliminal: We receive it, but we are not consciously aware of it. Over the yearsthere has been a great deal of speculation about the use of subliminal messages inadvertising, rock music, and self-help audio programs. Research evidence shows that inlaboratory settings, people can process and respond to information outside of awareness.
But this does not mean that we obey these messages like zombies; in fact, hiddenmessages have little effect on behavior outside the laboratory (Kunst-Wilson & Zajonc,1980; Rensink, 2004; Nelson, 2008; Radel, Sarrazin, Legrain, & Gobancé, 2009; Loersch,Durso, & Petty, 2013).

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Term
Fall
Professor
Tromp
Tags
Daniel Simons, Segall

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