Sensation and Perception

Sensation and Perception

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• 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

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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

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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

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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

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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

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