Sensation and Perception Flashcards
Sensory Receptors
•Specialized neurons that respond to specific types of stimuli
Occurrence of Sensation
- Sensation occurs when sensory information is detected by a sensory receptor
- Example – light that enters the eyes causes the chemical changes in cells that line at the back of the eye. These cells relay messages, in the form of action potentials, to the nervous system
- Not all sensation result in perception
Transduction
•The conversion from sensory stimulus energy to action potential
What are our senses?
- Vision
- Hearing (audition)
- Smell (olfaction)
- Taste (gustation)
- Touch (somatosensation)
- Vestibular Sense (balance)
- Proprioception and Kinesthesia (body position and movement)
- Nociception (pain)
- Thermoception (temperature)
Absolute Threshold
- Refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time
- Generally measured under incredibly controlled conditions in situations that are optimal for sensitivity
- May be influenced by motivation, experience and expectations
Difference Threshold (jnd)
- The minimum difference in stimulation that a person can detect 50% of the time.
- Changes depending on the stimulus intensity
Weber’s Law
•The difference threshold is a constant fraction of the original stimuli
Perception
•Refers to the way sensory information is organized, interpreted, and consciously experienced
Bottom-up Processing
•Refers to the fact that perceptions are built from sensory input
Top-down Processing
•Interpretations of those sensations that is influenced by our available knowledge, our experiences, and our thoughts
Sensory Adaption
•Individuals often don’t perceive stimuli that remain relatively constant over prolonged periods of time
Inattentional Blindness
•The failure to notice something that is completely visible due to lack of attention
Signal Detection Theory
•Ability to identify a stimulus when it is embedded in a distracting background
Muller-Lyer Illusion
- Lines appear to be different lengths although they are identical.
- Arrows at the ends of the lines may make the lines appear longer or shorter
Amplitude
•The height of a wave measured from the highest point on the wave (peak or crest) to the lowest point of the wave (trough)
Wavelength
- Length of a wave from one peak to the next
* Directly related to the frequency at a given wave form
Frequency
- Refers to the number of waves that pass a given point in a given time period
- Often expressed in terms of hertz (Hz), or cycles per second
- Longer wavelength will have lower frequencies, and shorter wavelength will have higher frequencies
Electromagnetic Spectrum
- Encompasses all the electromagnetic radiation that occurs in our environment
- Includes gamma rays, x-rays, ultraviolet light, visible light, infrared light, microwaves and radiowaves
Wavelength of Light (ROYGBIV)
- Our experience of Red is associated with longer wavelengths
- Greens have intermediate wavelengths
- Blue and violets are shorter in wavelengths
Amplitude of Light
- Associated with our experience of brightness or intensity of color
- Larger amplitudes appearing brighter
High-frequency Sound Waves
•Perceived as high-pitched sounds
Low-frequency Sound Waves
•Perceived as low-pitched sounds
Audible Range of Sound Frequencies
- Between 20Hz and 20000Hz
* Greater sensitivity to those frequencies that fall in the middle of this range
Amplitude of Sound Waves
- Higher amplitudes are associated with louder sounds
* Loudness is measured in terms of Decibels (dB)
Eye
•Major sensory organ involved in vision
Light Waves
•Transmitted across the cornea and enter the eye through the pupil
Cornea
- It is the transparent covering over the eye
- Serves as a barrier between the inner eye and the outside world
- Involved in focusing light waves that enter the eye
Pupil
- Is the small opening in the eye through which light passes
* When light levels are high, the pupil will constrict to reduce the amount of light that enters the light
Iris
- A thin, annular structure in the eye, responsible for controlling the diameter
- Colored portion of the eye
Lens
•Attached to muscles that can change its shape to aid in focusing light that is reflected from near or far objects
Fovea
- Part of the retina; light-sensitive lining of the eye
* Contains densely packed specialized photoreceptor cells, known as cones
Cones (Photoreceptor Cells)
- Light-detecting cells
- Specialized types of photoreceptors that work best in bright light conditions
- Sensitive to acute details
- Provide tremendous spatial revolution
- Directly involved in out ability to perceive colors
Rods
- Located throughout the remainder of the retina
- Specialized types of photoreceptors that work well in low light conditions
- Lack spatial resolution and color function
- Involved in our vision in dimly lit environments as well as our perception of movement on the periphery of our visual field
Night Blindnes
- A condition whereby rods do not transform light into nerve impulses as easily and efficiently as they should
- Difficulty seeing in dim light
Retinal ganglion cells
- Process visual information that begins as light entering the eye and transmit it to the brain via their axons, which are long fibers that make up the optic nerve.
- Over a million retinal ganglion cells; allow you to see as they send the image to your brain
Optic Nerve
•Carries visual information from the retina to the brain
Blind Spot
- An obscuration of the visual field.
* When light from a small object is focused on the blind spot, we do not see it
Optic Chiasm
- An x-shaped structure that sits just below the cerebral cortex at the front of the brain
- Information from the right visual field (which comes from both eyes) is sent to the left side of the brain and vice versa