Sensation The process by which our sensory receptors receive stimulus energies from our environment. Sensory receptors detect millions of stimuli.

Bottom-up Processing Sensory analysis at entry level. Detecting and analyzing sensory stimulus. Very quick, rapid analysis.

Top-down Processing Combination of our bottom-up processing and our bias, experience, and expectations to construct perceptions. Slower, more in depth analysis.

Psychophysics The study of relationships between the physical characteristics of stimuli and our psychological experience of them. What stimuli can we detect? How sensitive are we to changing stimuli?

Absolute Threshold The minimum stimulation necessary to detect a stimulus 50 % or more of the time. An example is a hearing test.

Signal Detection Theory A theory predicting how and when we detect the presence of a faint stimulus amid background stimulation. Detection depends on motivation, experience, expectations, and level of fatigue.

Subliminal Stimulus Stimuli that is below your absolute threshold meaning there is a less than 50% chance of detection. Can be subconsciously detected. Subliminal stimuli can “prime” your brain and influence your perceptions.

Just Noticeable Difference (JND) The minimum difference between two stimuli required for detection 50% of the time. Also known as difference threshold.

Weber’s Law The principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage. The greater the intensity of a stimulus the greater the chance of detecting a difference. Light= 8% difference Object= 2% difference in weight Tone=.3% difference to detect

Weber’s Law Demonstration Turn your desks to face the teacher’s desk… no looking at screen. Listen to detect sound. Raise your hand when you hear the music. _JM _JM

Sensory Adaptation Diminished sensitivity to a stimulus that is constantly present.