initial process of detecting and encoding environmental energy

EX: extracting characteristics of sounds

product of psychological processes

EX: recognizing melody

focuses on how perception occurs in env. by:

-emphasizing the moving observer-how perception occurs as the obs. moves thru scene

-identifying the info in the env. the obs. uses for perception

object in env. that offers a particular action

EX: door handle, coffee cup

80%

20%

Focusing Light on the Retina

-cornea =        % focusing power

-lens =       %, but can change shape according to distance

Iris and Pupil

2-9mm

adjustable aperture; limit the amount of light passing through

pupil b/t      -    mm

multiple rod cells converge on a single interneuron/RGC, collecting and amplifying signals

less acuity/image resolution

Horizontal-Amacrine

Bipolar-Retinal Ganglion

signals travel horizontally via           and               cells

signals travel vertically via            and               cells

        Cones ~6 million     Rods ~120 million

Yes        No  

Fovea       Periphery

High        Low

Low         High

Day/Photopic          Night/Scotopic

Rapid        Slow

Rods vs. Cones Contrast

Color Vision:

Retinal Location:

Spatial Acuity:

Sensitivity:

Luminance:

Dark Adaptation:

Acuity

Sensitivity

-ability to detect, resolve, and perceive fine details

-ability to detect a stimulus presence

2 varieties:

Large = M cells (magnocellular) carry info about dynamic aspects of the world (EX: movement and flicker)

Small = P cells (parvocellular) carry info about color

Optic Nerve

Optic Chiasm

Optic Tract

-ganglion cell fibers leave retina along      

-cross over point of optic nerves coming from eyes 

-beyond said cross over point [image]

Receptive Field

Excitatory and Inhibitory

part of the visual field (or that part of the retina) in which a visual stimulus elicits a change in the firing rate of a cell

-2 regions:         and        

-Receptive Field Sizes at Fovea and Periphery

Center-Surround Antagonism

-Center-Surround Antagonism

-Hermann Grid explained by

-Simultaneous Lightness Contrast and Mach Bands explained by

fovea = .01% of retina but is represented by

8-10% of V1

Retinal Ganglion or LGN cells; center-surround

Simple Cell

Complex Cell

Hypercomplex/"End-Stopped" Cell

receptive fields increase in complexity beyond the LGN:

         RFs respond to spots of light

          RFs respond to oriented bars/edges of partic. orientation; discrete +/- regions

          RFs respond to moving oriented bars/edges of a partic. orientation & direction; NO discrete +/- regions

         RFs respond to moving oriented bars/edges of a partic. orientation & direction of different sizes

V3

V4

V5 (MT)

visual areas beyond V1 (over 30!):

    specialized for:

form

color

motion

Ventral/What Stream

Dorsal/Where Stream

Visual Agnosia-damage to 'what'

Optic Ataxia-damage to 'where'

Inferotemporal Cortex (IT)

-impt. for recognizing objects and form representation, EX: color; main input from P layers of LGN

-impt. for det. where an obj. is and how to act on it/"visually-guided action", EX: reaching; main input from M layers of LGN

-evidence for Dual Stream Hypothesis

-face-sensitive cells in this region

-concerned w/ the rep. of edges, contours, and other areas of contrast change

-bottom-up/computational approach

-starts w/ input to perceptual sys. in form of retinal image and describes the stages in process

-each stage takes as its input the info from the prev. stage and transforms it into a more complex representation

Retinal Image

[image]

Gray Level Description

[image]

Primal Sketch

[image]

2 1/2D Sketch

[image]

3D Representation

-measuring intensity of light at each pt. in image

-rep. of contrast change (blobs, edges, bars, etc.) over range of spatial frequencies

-rep. of orientation, depth, color relative to obs.; analyzed for 3D volume primitives

-rep. of objects independent of obs.

Gestalt Approach

Segregation and Grouping

"whole is greater than sum of parts"

-sought to isolate principles of perception

-top-down approach

Similarity

Good Continuation

Proximity

Connectedness

Closure

Common Fate

Familiarity

Invariance

Pragnanz-good figure

Gestalt principles of perceptual organization:

Symmetry

Convexity: convex = figure

Area: smaller area = figure

Orientation

Meaning/Importance

Convergence

Accommodation

(OM cues)

-correlated w/ distance of obj. observed; only effective at 5-10 ft.

-feeling experienced as your eye muscles cause your eyes to look inward

-as the lens bulges to focus on a near object (African chameleon)

(Monocular Cues)

Overlap, Interposition, or Occlusion

Relative Size

Relative Height: lowest;highest

Atmospheric Perspective

Familiar Size

Linear Perspective

Shading and Shadows

Texture Gradient

and MOTION PARALLAX

-one object obscures part of another, or overlaps w/ it

-retinal size of objects gets smaller as they get further away

-as objects get further away, get nearer the horizon: obj. above/below eye height     ;      object = further away

-distant objects appear less sharp bc more air/particles to look through; more blue bc more blue light scattered by atmosphere

-lines that are parallel in the scene converge as they get further away

 -shadow/shading cue depth dep. on direction of light source

-texture becomes smaller/finer as dist. inc.

Size Constancy

decrease; increase

the fact that an object can look the same size regardless of changing retinal image size

-increase distance:          retinal image size

-decrease distance:          retinal image size

(Movement-Produced Cues)

Motion Parallax

Deletion

Accretion

-as an obs. moves relative to a 3D scene, nearby objs. appear to move rapidly while far ones move slowly

-as one obj. moves in front of another, front obj. covers more of the back obj.

-as one obj. moves away from another, front obj. covers less of back obj.

Binocular Disparity

(Binocular Stereopsis)

Non-Corresponding Retinal Pts.

depends on two eyes and fact that our eyes see the world from slightly different positions det. by the distances b/t them

-disparity created by          

- 2-5% people are stereo-blind

misalignment of the eyes-failure to converge on a common target; in early childhood prevents the normal development of binocular disparity detecting cells in the visual cortex

-usual cause of stereo-blindness

present same image to both eyes, but shift one slightly to the left or right, shifted area will appear displaced in depth (3D)

-made by: random dot stereogram, color filters, orthostereography, shutter glasses

Hue (Color): red and blue

Brightness (Perceived Intensity): light and dark blue

Saturation (how much white light is mixed in w/ the pure hue): red and pink

Properties of Light and Psychological Attributes:

Wavelength =      

Intensity =      

Spectral Purity =      

and EX:

Absorbs      Reflects        We See

Red      Blue&Green      Cyan

Blue      Red&Green      Yellow

Green      Blue&Red      Magenta

All Wvlghs      Nothing         Black

Mix             We See

Red&Green      Yellow

Red&Blue      Magenta

Blue&Green      Cyan

Red&Blue&Green        White

3 different sorts of receptors and they respond to diff. wavelengths of light; short, medium, and long cones; pigments in cones det. response; break down = bleaching

-Blue-sensitive (S): 419 nm

-Green-sensitive (M): 531 nm

-Red-sensitive (L): 558 nm

3 processes opponent in nature:

-red-green

-yellow-blue

-black-white

Cones

LGN and Cortical Cells

-trichromacy is correct at the level of the      

-opponent processes at the level of the      

Anopia

Protanopia

Deuteranopia

Tritanopia

insensitive to L,M, or S wavelength (missing a type of cone)

-L-cone missing

-M-cone missing

-S-cone missing

misalignment of L or M in trichromats (distribution or deficiency)

-L-cone pigment deficiency (need more red in red/green to make yellow)

-M-cone pigment deficiency (need more green in red/green mix to make yellow)

Deuteranomaly

Protanomaly

Protanopia

Deuteranopia

Tritanopia

Tritanomaly

Achromatopsia

Random Dot Kinematograms

-we don't need to be able to recognize an object to see it move

-we DON'T match edges and contours b/t successive views

present each image of dots one after the other after a short time lag

-suggest...

matching 2 images point-for-point over time

-RDKs suggest that motion detection is direct (aka we don't match point-for-point)

Real Movement

Apparent Movement

Induced Movement

Autokinetic Movement

Movement Aftereffects

detecting motion:

-change the          to get the other direction

-change the          to get different speeds

two images moving across the visual field at different speeds can be perceived as moving at the same speed

-affected by surroundings plus size of the moving object and framework through which it moves

if there is a difference b/t eye muscle movement and movement of image across the retina, we perceive movement

EX: tracking car-eye muscles move, but retinal image stays the same

EX: obj moves-eyes still, retinal image moves

EX: looking around-eyes move, and retinal image moves

Apparent Movement

(Stroboscopic Movement)

no movement/simultaneous

partial movement

optimum movement

phi movement-movement appears to occur, but difficult to actually perceive an object moving across space

no movement/successive

illusion of movement b/t 2 lights by flashing one light on and off, waiting 40-200 msec, then flashing other light on and off

< 30 msec =

30-60 msec =

~ 60 msec =

60-200 msec =

> 200 msec =

apparent movement:

as distance increases, either the          or the          must be increased to maintain the same perception of movement

if an observer first views a pattern moving in one direction, then views a spot of light, the spot (and surroundings) will appear to move the opposite direction

EX: waterfall illusion

Air pressure changes/waves

Perceptual Phenomenon: Pitch

Loudness (decibels)

Timbre (quality of the sound)

sound is...

characteristic of the sound wave: frequency (Hz)

amplitude (intensity)

complexity

Fundamental Frequency

Harmonics

Fourier Analysis of a Sound Wave

-         is the wavelength of the longest component; det. the pitch

-          det. the timbre

Basilar Membrane; Helicotrema

Organ of Corti

-traveling sound wave is transmitted through the 

           with the end at the           

-hair cells in the           detect vibrations in the [image]

They are bent; Potassium

Tonotopic

hair cells in ear change their rate of firing when 

           and release          

-they respond preferentially to a partic. frequency =         

Air Pressure Changes (Kinetic)

Vibration of Eardrum>Middle Ear>Oval Window (Mechanical)

Cochlear Fluid Flows (Kinetic)

Hair Cells Bend (Mech.)

Auditory Nerve Fires (Neural)

Monaural Space Perception

Binaural Space Perception

Head Shadow Effect

-loudness; Doppler effect

-interaural intensity and time (up to .07 sec) differences

-sound to one ear must travel further and diffuse around the head, it is attenuated

sounds grouped into streams by proximity in: space, time, frequency

-brain perceives continuity of sound when briefly interrupted by white noise

superposition of sine waves separated by octaves and intensity, but as the they all ascend/descend a scale drops out and begins again

"auditory barber pole" 

speech stripped of acoustic cues

knowledge of the sentence helps recognition

1.8 m²

5 kg

Glabrous; Hairy

Skin:

Area =

Weight =

-2 types:         :palms of feet and hands and

       :everywhere else

Fine details

Flutter

Stretching

Vibration/Fine texture

Paccinian > Meissner

Types of Tactile Receptors:

Merkel's Disc =

Meissner Corpuscle =

Ruffini Organ =

Paccinian Corpuscle =

-varied size of receptive field:       >      

Two-Point Discrimination/Threshold

2 mm

3.5 mm

100

the smallest separation of 2 separate but adjacent points of stimulation on the skin that just produces 2 distinct impressions of touch;

finger tip =

arm =

-# of receptors:      x more receptors/cm² on fingertip

Spatial Cues

Temporal Cues

-large surface elements (bumps and grooves) felt when moving hand across surface and when pressed onto elements

-ONLY when skin moves across a textured surface (fine sandpaper); info in form of vibrations

activity in:

-Primary and Secondary Somatosensory Cortices

-Superior Parietal Areas

Brain Imaging in Healthy Participants

-What object was

-Where object was

A delta fibers

C fibers

-fast pain (sharp/shallow)

-slow pain (dull/deep); mild stimulation may be pleasurable

Proprioception

Kinesthesis

-sensing where your body is in space; signals from muscles and vestibular system

-sense of movement and position of limbs in space

-can discriminate up to 10,000 types of molecules; 350 olfatory receptors (receptors of similar type project to same glomerulus)

-limited by our memory what they indicate

-no satisfactory classification

Orthonasal

Retronasal

2 routes for smell:

-via inhalation

-during chewing/swallowing

vivid memories brough back by smell of cookies

-close linkage b/t smell and the limbic system in the brain (emotion)

single neuron may respond to more than one modality

-orbitofrontal cortex: taste and smell

-posterior parietal cortex: touch, vision, audition

Distortions: Muller-Lyer, Ponzo, Poggendorff, Wundt/Hering, Titchler

Ambiguous Figures: Necker cube, Rubin vase

Paradoxical Figures: Penrose impossible objs.

Fictions: Kanizsa triangle

Muller-Lyer Illusion

Misapplied Size Constancy

two lines with either IN or OUTward fins

-misapplied size constancy: "inside corner" looks further away thus size-distance scaling causes this line to look longer

-NOT cross-cultural

two lines converge toward a 'vanishing' point-gives impression that line nearer [image] is further, thus larger

-when lines converge at bottom, there is little perspective; apparent depth is diminished, lines appear essentially same length

straight line passing behind a rectangle

-when the angle b/t the line and box increases, the misperception when lining up the 2 lines decreases

straight lines appear to bow out/in in the center bc radiating lines may be interpreted in terms of depth, seeing central pt. as further/closer

-thus, the lines must also be further/closer making your brain think they must be more widely/closely spaced

Ebbinghaus/Titchener Illusion

Relative Size

two equal circles with different framing

-brain overemphasizes differences in grouping and separating objects

cube appears to flip so red dot in sometimes inside/outside the cube

-brain visualizes 3D cube from 2D drawing, but not enough info to know which face of cube is at front

-visual sys. has hypothesis that cube is at one orientation, then another hypothesis is favored and cube flips

unreal shapes in the Kanizsa triangle illusion

-common to see near objects as blocking view of distant ones

-usu. near obj. looks brighter than a more distant one of the same color

-room appears cubic when viewed monocularly from a special pt. & obj. appear to grow/shrink going one corner to the other

-perceive ppl as same distance away, but one has much smaller visual angle, thus must be shorter