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.• https://

www.youtube.com/watch?v=nfWlot6h_JM

Sensory Adaptation• Diminished

sensitivity to a stimulus that is constantly present.