psy201 midterm #2

Cause and effect: causation does not equal correlation

2. Research cycle –

hypothesis: prediction based on the theory

theory: an explanation based on observations

3. Brain structures relevant to perception and their function (specifics below).

4. Neural integration and coding of

information (specifics below).

5. Features of cortical organization:

functional specialization: different parts of the cortex serve different functions

topographic organization: sensory and motor areas contain a map of the rector surface or muscles (think of the weird image)

contra-lateral connections: the right side of the cortex is connected to the left side of the body and vice versa

Asymmetry of higher functions (as relevant to visual processing): hemispheric speciation: being right-handed but better at drawing the figure with the left hand or lateralization: the left hemisphere is more important for language, Math & Logic skills and the right hemisphere is more important for spatial abilities, Face recognition & Visual imagery

primary sensory areas: receive input from sensory surface

primary motor area: sends axons down to motor neurons in the brain stem and spinal cord

association areas: regions of the cerebral cortex that do not have a specific sensory or motor function (ex: prefrontal association area

frontal areas: frontal lobe is home to areas that manage thinking, emotions, personality, judgment, self-control, muscle control and movements, memory storage and more

7. features of topographic maps: they are distorted and plastic; cortical magnification factor:

maps are distorted– the amount of cortex devoted to each part of the receptor surface or muscles does not correspond to the size of the body part. Maps are plastic--eg, training as a pianist reorganizes both the auditory and finger

representations in people

cortical magnification factor

describes how much of the brain's visual processing power is allocated to different parts of the visual field.

Sensation and Perception:

8. Sensation vs. Perception

Sensation: the detection of external stimuli and the

transmission of this information to the brain

perception: the processing, organization, and

interpretation of sensory signals

Psychophysics- a subfield developed during the

nineteenth century by the researchers Ernst

Weber and Gustav Fechner, examines our

psychological experiences of physical stimuli

methods: x

psychophysical function: x

psychophysical judgments: x

10.

Detection: detection theory (SDT): a theory of

perception based on the idea that the detection

of a stimulus requires a judgment—it is not an

all-or-nothing process

Signal detection research involves a series of trials in which a stimulus is presented in only some trials. In each trial, the participant must state whether he or she sensed the stimulus.

Discrimination: Signal detection theory: can measure discrimination independent of response bias

d’ (discriminability) is a measure of how well someone can detect signal from noise

Scaling (magnitude estimation): Determines the relationship between the actual and the perceived intensities for supra-threshold stimuli (Any stimulus that is strong enough to be not only detected but also perceived with variations in intensity.).

11. Psychophysical judgments:

Thresholds:

Weber’s law: Just-noticeable-difference is based on relative proportions of stimuli. The discrimination threshold (jnd) is a constant proportion (K, the Weber fraction) of the magnitude of the standard stimulus (S) for a sensory system.

(your ability to notice a difference depends on the relative size of the change compared to the original stimulus, not the absolute amount added.)

12. Signal detection theory – A psychophysical technique for estimating an observer's sensitivity to a signal independent of response bias.

hits: Yes/Present

misses: No/Absent

correct rejections: No/Absent

false alarms: Yes/Absent

liberal responders: more likely to say yes then no

conservative responders: more likely to say no then yes

13. Visual search: observers look for one stimulus in a set of many stimuli

feature and conjunction–

Conjunction/Conjunctive search to find the odd one out: Distractors share more than one feature with the target (but one-at-a-time!) Each distractor differs along one feature, but the scene has multiple feature distractors

- (When searching for an object in a visual scene, your brain uses two main types of search processes: feature search and conjunction search. These are part of visual search tasks in cognitive psychology, where you look for a target among distractors.

Feature Search (Easy & Fast): You are looking for a target that differs from all distractors based on a single feature (like color, shape, or size).
Conjunction Search (Harder & Slower): The target shares multiple features with the distractors, but no single feature is unique to the target.)

response times: gives an estimate of processing time, reaction time is the time from presentation of stimulus to observer’s response is measured

distractor effects: if target differs in only a single feature the target may “popout”. The more different the target, the more it pops out. This happens because we tend to process the scene holistically.

14. Perceptual cycle- Transduction: turning physical stimuli from the world into neural signals in the brain (action potentials)

Neural processing: original neural signals bound/integrated with others, sent to “higher” areas to be processed further.

(This means that the brain combines information from different sensory modalities [vision, hearing, touch, etc.] and different features of the same object [like its color, shape, and motion] to create a unified perception. Once basic info is collected it’s sent to higher areas. These "higher" areas (like the prefrontal cortex or temporal lobe) are responsible for more complex cognitive functions such as object recognition, memory, and decision-making.)

Perception: an awareness of the experience

Recognition: match current perception with memories…

Action: leading you to perhaps do something, which may change future perceptions

Knowledge: previous experiences color current perceptions

15.

Bottom-up processing: perceptual processing that relies only on information available in the sensory input. (without influence from prior knowledge.)

Top-down processing: Perceptual processing that relies on prior knowledge of the properties of the objects or events to be detected.

16. Senses (in general terms):

vision: stimulated by light waves. Light-sensitive rods and cones in the retina of the eye.

optic nerve

hearing: stimulated by sound waves. Pressure-sensitive hair cells in the cochlea of the inner ear

auditory nerve

touch: stimulated by pressure on the skin. Sensitive ends of touch neurons in the skin

cranial nerves for touch above the neck
spinal nerves for touch elsewhere

taste: molecules dissolved in fluid on the tongue. Cells in taste buds on the tongue

- Facial Nerve (Cranial Nerve VII):

taste sensation on the front two-thirds of the tongue.

- Glossopharyngeal Nerve (Cranial Nerve IX):

taste sensations on the back one-third of the tongue.

- Vagus Nerve (Cranial Nerve X):

taste sensation from the throat and palate areas.

smell: molecules dissolved in fluid on membranes in the nose. Sensitive ends of olfactory mucous nervous in the mucous membranes

Olfactory nerve

balance ("vestibular" sense): perception of balance determined by receptors in the inner ear in semicircular canals

limb position: the ability to determine location and orientation of limb segments with respect to each other and with respect to the external environment without vision

limb movement ("kinesthesis"): perception of the positions in space and movements of our bodies and our limbs

temperature: the degree of hotness or coldness of an object or environment

pain:

Free nerve endings:

receptors for pain reside in

skin as well as in internal

tissues.

Fast fibers for sharp pain
Slow fibers register dull, diffuse pain

Different types of pain

results from stimulation of

these receptors in different ways.

Gate control theory:

Complex regulation of pain
ex/ slapping mosquito bites to make them hurt/itch less

17. Receptors –

types, properties of receptors: Transduction, coding of stimulus quality and quantity,

18. properties of sensory systems:

receptive fields: x

topographical organization: representations in sensory systems are organized based on receptive fields. Neighboring areas of the body/environment are presented by neighboring sets of neurons.

(Topographical organization means that the brain organizes sensory information in a way that mirrors the layout of the body or the environment. Neighboring body parts or environmental areas are processed by neighboring neurons, which helps maintain spatial relationships and allows for efficient sensory perception.)

Adaptation: sensory adaption is sensitivity to signal decreases over time if the same stimulus persists. Helps detect new stimuli, focus on changes in the environment.

Threshold: The minimum intensity of stimulation necessary to detect a sensation half the time.

sensory neurons: x

sensory areas in the cortex: auditory, visual, gustatory, olfactory, and somatosensory cortices

representational maps/cortical magnification: Higher the sensitivity larger the number of neurons (with less overlap in receptive fields!) Representation is proportional to sensitivity (or fine control for motor areas).

Visual Perception:

19. Visual stimulus (light) and eye structure-

retina: the light-sensitive tissue that lines the back of the eye

Fovea:

Small, central region of the retina that is responsible for sharp central vision.
Contains a high concentration of cones (responsible for high-resolution vision and color perception.)
Crucial for tasks like reading, recognizing faces, and seeing fine details.
Located in the center of the retina, when we focus on an object, the light from that object is directed toward the fovea for most detailed perception.

blindspot: An area on the retina where the optic nerve leaves the eye. This region does not have any photoreceptor cells (rods or cones), so it cannot detect light.

20. Photoreceptors:

rods: outside of the fovea

More sensitive to light; operate at night
- More visual pigment
- More efficient chemical cascade
- Saturate in daylight

Scotopsin more sensitive to lower wavelengths

cones: concentrated in the fovea

Less sensitive to light; operates during the day
- Less visual pigment
- Less efficient chemical cascade
- Saturate only in intense light

Photopsin more sensitive to higher wavelengths

Responsible for color vision: 3 kinds, each sensitive to different wavelengths (color) of light

21. Retinal circuits:

Vertical connections for contrast enhancement and edge detection: x

Horizontal connections for contrast enhancement and edge detection: x

22. “Lateral inhibition” (e.g. Hermann grid) – contrast enhancement. (e.g. why do we see afterimages)

Lateral inhibition: Neighboring cells inhibit each other in

neural circuits, that results in contrast enhancement at the edges of visual stimuli.

Visual systems are sensitive to edges
If a rod or cone is stimulated, it sends information to is neighboring receptors, inhibiting their activity

23. Higher processing in the cortex – processing streams past V1.

24. Visual pathways - 2 “streams” of processing in primate visual cortex: Dorsal/“what” pathway (to the parietal lobe) & Ventral/“where” pathway (to the temporal lobe)

25. Effects of attention, context, and integration in higher visual processing

Perception of Color, Objects, Depth & Motion

26. Color perception: trichromatic theory – 3 cones

27. Opponent processes – R/G, Blue/Y, Black/W

28. Object form perception – feature integration and

form perception in the brain (ventral stream, IT modules

29. Gestalt principles/grouping principles

The Gestalt principles of stimulus organization account for some of the brain’s perceptions of the world

Those perceptions involve cues about similarity, proximity,

form, figure and background properties, shading,

Meaningfulness

(the Gestalt principles explain how our brain organizes what we see into meaningful patterns. Instead of just looking at individual pieces of information, our brain groups things together in ways that make sense. )

30. Heuristics – best guesses based on context and experience. “Best guess rules” (not algorithms)

Heuristics are related to top-down processing
We take context and prior experience into account when interpreting objects

31. Depth perception:

monocular (pictoral) cues: Pictorial cues use information from the object’s appearance relative to the surroundings to perceive depth and relative motion

(These are cues we use to perceive depth and distance in a scene using just one eye.)

binocular cues: An object’s pattern of stimulation on each of the two retinas informs the brain about depth

(These cues rely on both of our eyes working together to help us perceive depth and distance.)

Horopter: Imaginary circle that passes through the point of focus

movement related cues and movement of eyes (convergence): x

32. Size perception – size-distance scaling and size constancy:

Perception of an object’s size remains relatively constant
This effect remains even if the size of the object on the retina changes
Changes in distance and retinal size balance each other
Perceptual constancy: The brain correctly perceives objects as constant despite sensory data that could lead it to think otherwise
The perceptual system’s ability to make relative judgments allows it to maintain constancy across various contexts
- Color, size, shape, lightness

qaZ33. Misapplied scaling – illusions (Ponzo, Ames): Lines that are actually parallel will converge in the image as distance increases.

34. Motion perception – when eyes move, when eyes don’t move:

If the retinal image is stationary during a movement of the eyes, the brain will perceive a moving object
If the image movement can be attributed to movement of the eyes, the brain will perceive a stationary object

35. Motion perception in the brain – rod system, specialized areas/modules in dorsal stream - MT(direction of motion),

MST(complex motion/optic flow

perception), STS(Biological motion)

Attention:

36. Role of attention in perception:

Preattentive stage - features of objects

are separated

Focused attention stage - features are

bound into a coherent perception

Attention serves as the “glue” between

the physiology of the what and where

streams

37. Endogenous vs exogenous attention

38. Early vs late selection

39. Cocktail party effect and shadowing

40. Results of lack of attention: inattentional blindness, change blindness, attentional blink, hemispherical neglect

41. Divided attention and multitasking

42. Effects of practice; controlled vs. automatic processes

43. Processing with attention vs. without attention

Conscious and Unconscious cognition**

44. What is Consciousness?

45. What is the global workspace model?

46. What does the cognitive unconscious refer to? Examples of influences of unconscious processing on cognition/behavior – priming,

47. Sleep as an adaptive, altered state of consciousness 48. Regulation of sleep, REM/non-REM sleep, brain activity and dreams

49. Other altered states of consciousness- hypnosis, etc **EMPHASIS ON CLASS NOTES for these topics – some sections of the chapter not covered, or not covered in detail. Use class notes to guide your readings.