Sensation and PerceptionWindows on the WorldWe understand the world through our senses, our windows on the worldOur reality, in fact, is dependent upon two basic processes:Sensation: Gathering informationPerception: Interpreting informationAn Example of MisperceptionThe JourneyHow the Physical World elates to the Psycholo!ical WorldHow We See and How We HearHow We Ma"e Sense of What We SeeHow the Physical World elates to the Psycholo!ical WorldThe Detection uestionThe Difference uestionThe !caling uestionThe #uestions"# The detection $uestion is concerned with the limits on our ability to detect %ery faint signals&ow intense does a light ha%e to be for us to see it' &ow intense does a sound ha%e to be for us to hear it'The #uestions(# The difference $uestion is concerned with limits on our detection abilities, but in this case with our ability to detect %ery small differences between stimuliWhat is the smallest difference in brightness between two lights that we can see' What is the smallest difference in loudness between two sounds that we can hear' The #uestions)# The scalin! $uestion is concerned with how we percei%e the magnitudes *intensities+ of clearly detectable stimuliWhat is the relationship between the actual physical intensities of stimuli and our psychological perceptions of these intensities' The $etection #uestionA%solute threshold is the minimum amount of energy in a sensory stimulus that is detected ,-. of the timeSu%liminal stimulus is one that is detected only up to /0. of the time 1ny effects of subliminal persuasion are short2li%ed with no long2term conse$uences on our beha%iorTheoretical and &%ser'ed A%solute Thresholds(our Possi%le &utcomes in a Si!nal $etection StudyPresent A%sent)*es+ Hit(alse Alarm ),o+ Miss-orrect e.ectionThe $ifference #uestion1 difference threshold *also called a .ust noticea%le difference, or .nd+ is the minimum difference between two stimuli that is detected ,-. of the timeWe%er/s 0aw says that for each type of sensory 3udgment, the difference threshold is a constant fraction of the standard stimulus %alue used to measure itThe Scalin! #uestionSte'en/s Power 0aw states that the percei%ed magnitude of a stimulus is e$ual to its actual physical intensity raised to a constant power for each type of 3udgment4or instance, to percei%e a light as twice as bright, its actual intensity has to be increased between and 5 and 0 times6i7ewise, if an electric shoc7 is doubled in intensity, we percei%e it as being about "- times more intenseThe Scalin! #uestionSensory adaptation is the disappearance to repetiti%e or unchanging stimuliThis sensory adaptation has sur%i%al %alue, as it is more important to detect new stimuli *which may signal danger+ than constant stimuliHow We See and How We Hear&ow the 8ye Wor7s&ow We !ee 9olor&ow the 8ar Wor7s&ow We Distinguish :itchPhysical -haracteristics of 0i!ht and Sound Wa'esWa'elen!th refers to the distance in one cycle of a wa%e, from one crest to the ne;tWith respect to %ision, human can see wa%elengths of about /-- to