psyc midterm chapter 4 Flashcards
What is sensation?
Detection of physical energy by our sense organs (light, smell, sound).
What is perception?
The brain’s interpretation of these raw sensory inputs.
What is transduction?
The nervous system converts an external stimulus into electrical signals within neurons. (for example auditory system; hair cells in the ear are where transduction occurs and where auditory information takes place).
When is sense activation the greatest?
The smallest change in the intensity of a stimulus that we can detect. (sensory receptors)
What is sensory adaptation?
Process in which activation is the greatest when stimulus is first detected. (sitting down, we feel it for the first couple seconds then we don’t constantly focus on it after)
What is psychophysics?
Study of how we perceive sensory stimuli based on physical characteristics (Gustav Fechner - 1860)
What is the absolute threshold of a stimulus?
The lowest level of stimulus needed for the nervous system to detect 50% of the time.
What is the just noticeable difference (JND) or difference threshold?
Is the smallest change in the intensity of a stimulus that we can detect. The JND is relevant tour ability to distinguish a stronger stimulus from a weaker stimulus (soft noise against a slightly louder noise) (Just Noticeable Difference).
What is Weber’s Law?
There is a constant proportional relationship between the JND and the original stimulus intensity, a proportionate increase.
What is Weber’s fraction?
Weber’s fraction is the constant ratio of the just noticeable difference (JND) to the initial stimulus intensity. It describes how much a stimulus must change for a person to detect the difference. The fraction remains constant for a given type of stimulus, meaning that larger stimuli require a larger absolute change to notice a difference, but the proportion (or fraction) stays the same.
What is the signal detection theory, and can you give an example of it?
Theory of how stimulus is detected under different conditions. (trying to hear someone’s call with poor cellular connection).
Do you know what response biases are?
Our tendencies to make one type of guess over another when we were in doubt about whether a weak signal is present or absent under noisy conditions. They developed a clever way to take into account some people’s tendency to say “yes” when they are uncertain and other people’s tendency to say “no” when they are uncertain.
Can you explain the difference between true positive (hit), false negative (miss),
false positive (false alarm), and true negative (correct rejection)? (there is a picture you should study!)
Hit: detect stimulus that was present.
Miss: fail to detect a stimulus that was present.
False alarm: indicate a stimulus was present, when it was not.
Correct rejection: indicate there was no stimulus, when there was no stimulus.
Are sensory systems independent?
No, sensory systems are not completely independent. While each sensory system (e.g., vision, hearing, touch) processes specific types of information, they often interact and influence each other. This is known as sensory integration. For example, vision can affect how we perceive sound (the McGurk effect), and touch can influence our sense of balance. Sensory systems work together to provide a more comprehensive perception of the environment.
Can you explain the McGurk effect?
Demonstrates that we integrate visual and auditory information when processing spoken language, and our brains automatically calculate the most probable sound given then information from the two sources. In the McGurk effect, hearing the syllable “ba” spoken readily while seeing a video track of a different syllable “ga” produces the perceptual experience of a different third sound “da”. This third sound is the brain’s best “guess” at integrating the two conflicting sources of information.
What is synesthesia? Can you give some examples of synesthesia?
Synesthesia is when people experience cross module sensations. Chromesthesia; sounds trigger the experience of colour, can trigger strong emotions such as anger or fear. Mirror-touch; a person experiences the same sensation that another person experiences, such as touch. Number-form; numbers are imagined as mental maps.
Describe the role of attention.
Our brains are immersed in a sea of sensory input, flexible attention is critical to our survival and well-being. Any moment we must be prepared to use our sensory information that signals a potential threat. (two roles of attention selective and inattentional)
What is Selective Attention?
Process of selecting one sensory channel and ignoring or minimizing others. The major brain regions that control selective attention are the reticular activating system and the forebrain.
Can you explain the cocktail party effect?
An attention related phenomenon refers to our ability to pick out important information from a conversation we aren’t engaged in or a part of.
What is Inattentional Blindness?
Failure to detect stimuli that we are in plain sight when our attention is focused elsewhere.
What is the binding problem?
Our brains manage to combine or “bind” these diverse pieces of information into a unified whole. Binding may explain many aspects of perception and attention. When we see the world, we rely on shape, motion, colour, and depth cues, each of which requires different amounts of time to detect individually. Yet our minds seamlessly combine these visual cues into a unified perception of a scene.
Light waves vary in amplitude, wavelength, and purity. How do amplitude, wavelength, and purity affect or impact the perception of light?
Visible light has a wavelength in hundreds of nanometres. We only respond to a narrow range of wavelengths of lights. Our perceptions of an object’s brightness is influenced directly by the intensity of the reflected light that reaches our eye.Amplitude: Affects brightness—greater amplitude results in brighter light, while smaller amplitude leads to dimmer light.
Wavelength: Affects color (hue)—different wavelengths correspond to different colors on the visible spectrum. For example, shorter wavelengths (around 400 nm) appear violet, and longer wavelengths (around 700 nm) appear red.
Purity: Affects saturation (color intensity)—higher purity (less mixture of wavelengths) results in more vivid, pure colors, while lower purity (more mixed wavelengths) produces duller, less saturated colors.
Do wavelengths have colour? Why or why not. Explain.
Mixing primary colors together to make pigment creates a certain wavelength, which leaves little or no color. Wavelengths themselves don’t have color; rather, they correspond to colors in the visible spectrum. When light of different wavelengths enters the eye, it is processed by the brain and interpreted as color. For example, a wavelength of about 480 nm is perceived as blue, and around 650 nm, it is seen as red. The perception of color is a result of how light interacts with the photoreceptors in our eyes, not an inherent property of the wavelengths themselves.
How does the eye see?
Reflected light enters the pupil, cornea and lens focuses light on the retina to form images. Once light hits the retina, receptors are activated lens which are capable of accommodation. Light rays will then reach the back of the eyes and form an image.
What are the main components of the eye? (look at diagram)
Optic nerve; transmits impulses from the retina to the rest of the brain.
Retina; innermost layer of the eye, where incoming light is converted into nerve impulses.
Eye muscle; one of the six surrounding muscles that rotate the eye in all directions.
Sclera- the white of the eye.
Pupil; opening in the center of the iris that lets in light. In charge of dilation and expansion.
Iris; coloured area containing muscles that control the pupil.
Cornea; curved, transparent dome that bends incoming light to focus the incoming visual to the back of the eye. Covers the iris and pupil.
Lens; transparent disk that focuses light rays for the near or distant vision.
What role does the cornea play in vision?
Its shape bends the incoming light to focus the incoming visual image at the back of the eye.
What role does the lens play in vision?
Bends light, changes curvature, allowing fine tune the visual image called accommodation. The lens changes shape to focus light on the back of the eye; this way the eye can perceive distances of objects.
What kinds of accommodations (or adjustments) can the lens make?
“Fat” which makes the lens short and wide allowing near vision. “Flat” makes the lens long and skinny allowing us to see distant objects.
How is light focused in the eye?
Light is focused in the eye through the cornea, lens, and pupil:
Cornea: When light enters the eye, the cornea (the transparent outer layer) bends (refracts) the light to begin focusing it.
Pupil: The pupil controls how much light enters the eye by adjusting its size, depending on the lighting conditions.
Lens: The light passes through the pupil and is further focused by the lens, which changes shape (via the ciliary muscles) to fine-tune focus for objects at different distances.
Retina: The focused light is then directed onto the retina, where photoreceptor cells (rods and cones) convert the light into electrical signals that are sent to the brain, creating a visual image.
This process ensures that light is focused accurately onto the retina for clear vision.
What is Presbyopia? And how does it interact with age?
As our vision tends to worsen as we become older our lens loses its flexibility overtime, this is called prebyopia.
What is the “near point?” How does near point relate to presbyopia?
The near point is the closest distance at which the eye can focus on an object clearly. For a young, healthy eye, this is typically about 10–15 cm from the eye.
Presbyopia is the age-related condition in which the lens of the eye loses its flexibility, making it harder to focus on close objects. As a result, the near point moves farther away because the eye’s ability to change the shape of the lens (to focus on nearby objects) declines. This is why people with presbyopia often need reading glasses or other corrective lenses to see objects up close.
Do you know the difference between Myopia and Hyperopia, and can you explain
each condition?
Myopia; nearsightedness results when images are focused in front of the rear of the eye due to the cornea being too steep or our eyes being to long. Makes this difficult to see far objects clearly.
Hyperopia; farsightedness results when our cornea is too flat or our eyes are too short. Inability to see near objects clearly.
What role does the retina play in vision?
Is able to absorb light, processes images and sends visual information to the brain, also contains the fovea.
What is the function of the fovea? Where is it located?
Fovea; central part of the retina and is responsible for acuity, or sharpness of vision, has no receptor cells creating a hole, sour our brain fills in the gap.
Can you describe what rods and cones are, what their functions are, and how
they are different from one another?
Rods; receptor cells in the retina allowing us to see in low levels of light and peripheral vision.
Cones; visual receptors that aid in daylight vision and colour vision.
Where are cones most densely located? Where are the rods most densely
located?
Both are found in the retina, rods are going to be more dense because they are long and narrow but also rely on low levels of light while cones require higher levels of light. But if we had too many cones the world would be blinding us continually.
Where is the blind spot located? What is the blind spot?
The blind spot is where the optic nerve connects to the retina that contains no rods, cones, or sensory receptors.
What is the Trichromatic Theory and how does it relate to colour perception?
Depends on the activity of three different = receptor types (red, green, blue). With three kinds of cones each maximally sensitive to different wavelengths of light.
