Sensation and Perception

• Sensation

  • The process of receiving stimulus and energies from the external environment and transforming those energies into neutral energies

• Perception

  • The process of organizing and interpreting sensory information so that it makes sense

Types of Processing-

• Bottom-up

  • The operations in S and P in which sensory receptors register info about the external environment and send it up to the brain for interpretation

  • Data-driven

  • Focus on incoming data

  • It takes place in real-time

• Top-down

  • The operation in S and P is launched by cognitive processing at the brain's high levels that allow the organism to sense what's happening and to apply that framework info to the world

  • Rely on contextual cues to interpret info

  • Use previous experience and expectations as cues

What's the Process?

• Reception

  • The stimulation of the sensory receptor cells by energy (sound, light, heat, etc.)

  • Psychophysics- the study of the psychological effect of the forms of energy

• Transduction

  • Transforming this cell stimulation into neural impulses

• Transmission

  • Delivering this neural information to the brain to be processed

Thresholds

• Absolute threshold

  • The minimum level of stimulus intensity needed to detect a stimulus half the time

  • Anything below this threshold is considered subliminal

• Signal detection theory- whether or not we detect a stimulus, especially amidst background noises

  • It depends not just on the intensity of the stimulus but also on psychological factors

• Subliminal Detection

  • Below our threshold for being able to detect a stimulus consciously

• Just noticeable difference

  • The minimum difference (color, pitch, weight, temp., etc.) for a person to detect the difference half the time

    • Weber's Law- for two stimuli to be perceived as different we must differ by a minimum percentage

      • Weight= 2%

      • Light intensity= 8%

      • Sound = 0.3% frequency

• Sensory adaption

  • To help detect more novel stimuli in our environment, our senses will tune out constant stimuli

    • When you switch your phone from one pocket to the other do you feel it?

    • The brain wants to focus on one sensation at a time

• Perceptual set

  • When what we EXPECT to see influences what we DO see

• Context effect on perception

  • Double pair apple pear payee payor

The Effect of emotion, psychical state, and motivation on perception

• Experiments have shown that

  • Destinations appear to be farther when your tired

  • Targets look farther when your cross bow is heavier

  • A hill looks steeper with a heavy backpack, or listening to sad music, or being alone