Cognitive Psychology

Cognition is…

Acquisition Storage Transformation Use of Knowledge

Structuralism (Wundt)

Defines psychology as a science of immediate experience Uses introspection

Introspection

A method used to study the structure of mind built from consciousness, eg describe experience of eating an apple. Limitation

Stimulus error

Describing an experience based on subjective interpretation rather than immediate experience

William James

Insisted on psychology as a functional science where the individual is an active being within an environment Introduced stream of consciousness concept

Stream of consciousness

A literary technique that represents the thoughts and feelings of a character as they occur.

James

Lange theory of emotion

Functionalism

Interested in function of conscious activity rather than the structure of consciousness

Mental processes are not studied as isolated independent events but as part of biological activity of the organism

John B Watson

Father of behaviourism

Behaviourism (Watson)

Subject matter of psychology is observable behaviour mental events cannot be observed therefore, should not be the subject of psychology

What does behaviorism work for and not work for?

Works for: Simple learning, Conditioning and Animal behaviour in controlled settings But it struggled with: Human experience of Language, Reasoning, Planning, Memory, Novel behaviour

Operant conditioning

Method of learning that occurs through rewards and punishments for behaviour

Development of Cognitive science

Interdisciplinary field that involved a number of disciplines and developed in the 1950s

Scientific method

Experimentation, observation, case studies

Step 1 of experimentation

Identify the problem and formulate a testable hypothesis

Step 2 of experimentation

Design the experiment

Step 3 of experimentation

Conduct the experiment

Step 4 of experimentation

Evaluate the hypothesis by examining the data

Step 5 of experimentation

Communicate the results

Limitations of experimentation

Ecological validity, external validity

Iris functions

regulates diameter of pupil to regulate how much light can be let into the eye

Lens function

Lens can be modified in shape, transparent layer that sits behind the pupil. Attached to ciliary muscles which contract or relax to focus on an object

Retina structure + processes

Outermost layer = retinal ganglion cells Middle layer = horizontal cells, bipolar cells and amacrine cells Then there is a layer of photoreceptors

two types of photoreceptors

rods and cones

Cones

sensitive to higher levels of light, sensitive to colour and have greater visual acuity

Rods

work very well in lower levels of light

Distribution of photoreceptors

Cones distributed at centre of retina. Fovea is the name for the centre of the retina. Rods are located on the outside of retina.

Retinal Ganglion Cells

P(Parvocellular) cells respond to colours, fine details and still or slow

Two visual pathways

Mangocellular = where pathway Pavocellular = what pathway

Optic chiasma

directs fibres from nasal retinas to cross to the opposite side, whilst fibres from temporal retinas remain on the same side. Allowing brain to merge visual input from both eyes into a single image

Where is right and left visual field located

Right visual field is all located on the left and vice versa

4 brain lobes and functions

1. Frontal lobe

Where does the primary visual cortex receive most of its input from?

The Lateral Geniculate Nuclei

Where does the secondary visual cortex receive most of its input from?

the primary visual cortex

Where does the Visual association cortex receive most of its input from?

the secondary visual cortex

dorsal stream of vision

Interprets spatial information (location/motion)

Ventral stream of vision

Interprets object characteristics (colour/shape)

Human visible spectrum of light

between infrared and ultraviolet

What wavelengths of light can we see?

400nm

we can describe colour along 3 dimensions…

Hue (name of colour)

Saturation (purity of the hue)

Lightness (degree of light reflected from the surface of an object)

Colour constancy

cognitive ability of human visual system to perceive colour of objects as constant despite significnat changes in intensity and composition of light sources

3 types of cones

Short cones

visual opponent process theory

we can't see any colours between red and green, some species can

what percent of males and females have problems with colour vision

8% males 0.4% females

Trichromacy

normal color vision

Dichromate

only 2 cones

Monochromacy

only one functional cone

Rod Monochromacy

a condition in which a person has rods only, with no cones, they see in black and white

What causes colour vision deficits?

cone abnormalities or damage to visual cortex (e.g. V4)

Cerebral achromatopsia

rare form of acquired colour blindness cause by brain damage / lesion in V4 (in the secondary primary visual cortex)

Form perception

the organization of the visual field into objects that stand out from their surroundings

Figure ground processing

Focusing on different subjects, whatever you focus on becomes the subject of attention Ability to become background rather than figure is crucial for survival for certain animals

Grouping

the perceptual tendency to organize stimuli into coherent groups

Conceive an object as having closed boundaries Our brain is able to reconstruct boundaries by visual cues or features

9 Grouping laws

Law of Proximity

When can babies perceive depth?

as young as 6 months old

Depth perception importance

allows us to do everything from driving to being able to pick up things

Visual Cliff experiment (Gibson and Walk 1960)

Toddlers were placed on a structure with a glass surface, creating a dramatic effect of a visual cliff Up to 5 months the babies keep going, don't perceive the visual cliff as dangerous From 6 months on, they stop at the cliff

What are monocular depth cues?

depth cues that help us perceive depth using only one eye

pictorial cues (monocular)

cues to depth perception that are used to convey depth in drawings and paintings

Interposition

Oculomotor cues (monocular)

Accommodation

Motion

produced cues (monocular)

Binocular cues of depth perception

depth cues, such as retinal disparity, that depend on the use of two eyes

1. Convergence

Akinetopsia

inability to detect motion, lack of function in visual area 5 (V5)

Motion perception

3 types

Stroboscopic movement

a type of apparent movement based on the rapid succession of still images, as in motion pictures

presents dot on 3 frames, our brain fills in the gap and sees 1 moving dot

Induced movement

incorrect perception of an object as moving

Auto

kinetic effect

Motion after

effect (Waterfall illusion)

Intrinsic factors of an object

its shape, surfaces, and parts

Extrinsic factors of an object

relate to variation in viewing conditions, such as position, lighting, occlusion, etc.

Object recognition

views, illuminations, occlusion, deformation, intra

View

independent theories

View

dependent theories

Biederman's 1987 "Recognition

By

Properties of Geons:

All sufficiently different from each other

Advantages + Disadvantages of Biederman's 1987 "Recognition

By

Gauthier et al., 1998 "training greeble experts"

Procedure:

Two pathways from the occipital lobe?

dorsal to the parietal lobe and ventral to the temporal lobe

Gross et al. (1970s)

monkeys

Agnosia

loss of recognition and identification of a previously learned stimulus disorder of object recognition

Visual Agnosia

Inability to recognize objects despite intact vision.=

3 types of visual agnosia

Apperceptive: Deficits in perceptual processing, failure to generate a percept, to form a pattern

Associative: deficits in associating a visual input with meaning, can replicate an image but unable to tell what it is

Category

face recogntion

Gauthier et al., (1998) " Activation of the middle fusiform 'face area' increases with expertise"

Procedure: Some participants were trained to recognise novel object (i.e., the Greebles) and became the 'experts'. All participants (i.e., novices and experts) were scanned while viewing Faces and Greebles Results: FFA activated for greebles in the Greeble experts group

Prosopagnosia

inability to recognise faces in the absence of other visual impairments

Attention

the set of mechanisms that allow us to select what is most relevant from moment to moment. Instead of treating every stimulus as equally important attention allows us to focus on the most important in that moment.

Selective attention

our ability to focus on one source of information while filtering out others

Cocktail

party effect

What is a classic method for studying selective attention?

dichotic listening

Controlled vs Automatic Attention

Controlled is slow, effortful and goal

Divided Attention

concentrating on more than one activity at the same time

Dual

task interference

Early selection

unattended info is blocked before meaning is processed

Attenuation

unattended info is weakened, not discarded

meaningful items can still break through

Late selection

all stimuli are processed for meaning

attention decides what reaches awareness

Spotlight metaphor

attention functions like a beam of light illuminating a region of space. Items within the beam are processed more quickly and accurately than those outside it.

2 key properties of attention

1. Selectivity

Zoom lens model

Attention does not always have a fixed size.

'beam' can be narrow