Ch.4 Flashcards
Transduction
Process of converting an external energy or substance into electrical activity within neurons. (External stimulus, like a light, or sound into electrical signals within neurons)
Sense receptor
Specialize cell responsible for converting external stimuli into neural activity for a specific sensory system. 
Sensory adaptation
Process in which activation is greatest when stimulus is first detected. 
-Our response declines in strength, after a few seconds, we no longer notice it. 
-adaptation takes place at the level of the sensory receptor.
Absolute threshold
Lowest level of a stimulus needed for the nervous system to detect a change 50% of the time. 
Psychophysics
The study of how we perceive sensory stimuli based on their physical characteristics
Just noticeable difference (JND)
The smallest change in the intensity of a stimulus that we can detect. 
-Relevant to our ability to distinguish a stronger stimulus from a weaker stimulus, like a soft noise from a slightly louder noise. 
Weber’s law
Principle stating there is a constant proportional relationship between the JND and the original stimulus intensity.
-The stronger the stimulus, the bigger the change needed for a change in stimulus intensity to be noticeable. 
Signal detection theory
Theory regarding how stimulus are detected under different conditions
-Signal to noise ratio: It becomes harder to detect a signal as background noise increases.
-Response biases: Tendency to make one type of guess over another when we’re in doubt about whether a weak signal is present or absent under noisy conditions. 
•True positive, or hit: People can afford that they’ve heard a sound when it was present.
•False negative, or miss: Deny hearing a sound when it was present.
•False positive, or a false alarm: Report hearing a sound that wasn’t there.
•True negative, or correct rejection: Deny hearing the sound that wasn’t there. 
Specific nerve energies
States that even though there are many distinct stimulus energies like light, sound, or touch— the sensation we experience is determined by the nature of the sense receptor, not the stimulus.
-Ex: rub eyes shortly after Waking up, try to notice phosphenes— vivid sensations of light caused by pressure on your eye’s receptor cells. It doesn’t matter to our brain whether light or touch activated the sense receptor: Our brains react the same way either case. That is once our Visual sense receptor send signals to the cortex, the brain interprets the input as visual, regardless of how our receptors were stimulated in the first place. 
McGurk affect
This effect demonstrates that we integrate visual and auditory information when processing spoken language, and our brains automatically calculate the most probable sound given the information from the two sources.
-Hearing “ba”, seeing “ga” and our brains best guess is at integrating the two conflicting sources of information is “da”.
Rubber Hand illusion
Shows how our senses of touch, and sight interact to create a false perceptual experience.
Synesthesia
A condition in which people experience Cross-modal sensations
Examples-
Mirror-touch synesthesia: A person experiences the same sensation that another person experiences, such as Touch. 
Lexical-gustatory synesthesia: Words associated with specific tests or textures.
Chromesthesia: Sounds trigger the experience of colour.
Personification: Numbers, letters, or days of the week take on personality characteristics and sometimes have characteristic appearances.
Number-form synesthesia: Numbers are imagines as mental maps.
Spatial sequence synesthesia: certain certain sequences of numbers, dates, or months are perceived as closer or farther in space.
Graphemes-colour synesthesia: And which 6 may always seem red and a 5 green.
Lexical-taste synesthesia: Words have associated tastes and in still others synesthesias letters take on “personality traits.”
Selective attention
Process of selecting one sensory channel and ignoring or minimizing others
-The major brain regions that control selective attention is the reticular activating system and forebrain. These areas activate regions of the cerebral cortex, such as the frontal cortex. 
Filter theory of attention
Views attention as a bottleneck through which information passes. This mental filter enables us to pay attention to important stimuli and ignore others. 
Cocktail party effect
Refers to our ability to pick out important messages, like our name in a conversation that doesn’t involve us.
Inattentional blindness
Failure to detect stimuli that are in plain sight when our attention is focussed elsewhere
Change blindness
Failure to detect obvious changes in one’s environment. 
Binding problem
When we perceive an apple, different regions of the brain process different aspects of it. Yet somehow—we don’t Really know how— Oh brains manage to combined or bind these diverse pieces of information into a unified whole. 
-One hypothesis is that rapid coordination activity across multiple cortical areas assist in binding.
-Binding May explain many aspects of perception and attention. When we see the world rely on shape, motion, colour, and depth cues, each which requires different amount of time to detect individually.
Pupil
Circular hole through which light enters the eye.
-Responds with the pupillary reflex to decrease the amount of light allowed into them. This reflex occurs Simultaneously in both eyes.
-Dilation (expansion) of the pupil also a psychological significance. our pupils dilate when we’re trying to process complex information. They also dilated when we view someone we find physically attractive.
Cornea and lens
Cornea: part of the eye containing transparent cells that focus light on the retina.
Lens: part of the eye that changes curvature to keep images in focus.
Accommodation
Changing the shape the lens to focus on objects near or far.
-“flat” (Long and skinny) Enables us to see distant objects.
-“fat” (Short and wide) Enables us to focus on nearby objects. 
Myopia and Hyperopia
Myopia (Nearsightedness)- Images are focussed in front of the rear of the eye, due to the cornea being too steep or our eyes being too long. Inability to see far objects well, with an intact ability to see close objects clearly.
Hyperopia (Farsightedness)- Results when our cornea is too flat or our eyes are too short. Inability to see near objects well, with an intact ability to see far objects clearly.
Retina, Fovea, and Acuity
-Membrane at the back of the eye responsible for converting light into neural activity.
-Central portion of the retina
-Sharpness of vision
Rods
Long and narrow, Enable us to see basic shapes and forms. Receptor cells in the retina allowing us to see low levels of light. There are no rods in the fovea. By relying on our Peripheral vision, We allow more light to fall onto our rods. Photopigment in rods is rhodopsin, vitamin A is needed to make it.
Dark adaptation- Time in dark before rods regain maximum light sensitivity. Takes about 30 minutes. 
Cones
Receptor cells in the retina allow us to see colour. Sensitive to detail; require more light than rods do. Different types of receptor cells contain photopigments, Chemicals that change following exposure to light.