the human sensory, short-term , long-term Information processed - PDF document

the human • Information i/ o … chapter 1 – visual, auditory, haptic, m ovem ent • Information stored in memory the human – sensory, short-term , long-term • Information processed and applied – reasoning, problem solving, skill, error • Emotion influences human capabilities • Each person is different Vision The Eye - physical reception • mechanism for receiving light and Two stages in vision transforming it into electrical energy • light reflects from objects • physical reception of stimulus • images are focused upside-down on • processing and interpretation of retina stimulus • retina contains rods for low light vision and cones for colour vision • ganglion cells (brain!) detect pattern and movement Interpreting the signal Interpreting the signal (cont) • Size and depth • Brightness – subjective reaction to levels of light – visual angle indicates how m uch of view – affected by lum inance of object object occupies – m easured by just noticeable difference (relates to size and distance from eye) – visual acuity increases with lum inance as does – visual acuity is ability to perceive detail flicker (limited) • Colour – fam iliar objects perceived as constant size – m ade up of hue, intensity, saturation (in spite of changes in visual angle when far away) – cones sensitive to colour wavelengths – cues like overlapping help perception of – blue acuity is lowest size and depth – 8% m ales and 1% fem ales colour blind 1

Interpreting the signal (cont) Optical Illusions • The visual system compensates for: – m ovement – changes in luminance. • Context is used to resolve ambiguity the Ponzo illusion the Muller Lyer illusion • Optical illusions sometimes occur due to over compensation Reading Hearing • Several stages: • Provides information about environment: – visual pattern perceived distances, directions, objects etc. – decoded using internal representation of language • Physical apparatus: – interpreted using knowledge of syntax, sem antics, – outer ear – protects inner and amplifies sound pragm atics – m iddle ear – transmits sound waves as vibrations to inner ear • Reading involves saccades and fixations – inner ear – chemical transmitters are released and cause impulses in auditory nerve • Perception occurs during fixations • Sound • Word shape is im portant to recognition – pitch – sound frequency • Negative contrast improves reading from – loudness – amplitude com puter screen – tim bre – type or quality Hearing (cont) Touch • Provides im portant feedback about environm ent. • Humans can hear frequencies from 20Hz to 15kHz • May be key sense for som eone who is visually im paired. – less accurate distinguishing high frequencies than • Stim ulus received via receptors in the skin: low. – thermoreceptors – heat and cold – nociceptors – pain • Auditory system filters sounds – mechanoreceptors – pressure (some instant, some continuous) – can attend to sounds over background noise. • Som e areas m ore sensitive than others e.g. fingers. – for exam ple, the cocktail party phenom enon. • Kinethesis - awareness of body position – affects comfort and performance. 2

Movement Movement (cont) • Tim e taken to respond to stim ulus: • Fitts' Law describes the tim e taken to hit a reaction tim e + m ovem ent tim e screen target: • Movement time dependent on age, fitness etc. Mt = a + b log 2 ( D/ S + 1) • Reaction time - dependent on stimulus type: where: a and b are em pirically determ ined constants – visual ~ 200m s Mt is m ovem ent tim e – auditory ~ 150 m s D is Distance – pain ~ 700m s S is Size of target • Increasing reaction tim e decreases accuracy in � targets as large as possible the unskilled operator but not in the skilled distances as sm all as possible operator. Memory sensory memory There are three types of m em ory function: • Buffers for stimuli received through senses Sensory m em ories – iconic m em ory: visual stim uli Short-term m em ory or working m em ory – echoic m em ory: aural stim uli – haptic m em ory: tactile stim uli • Examples Long-term m em ory – “sparkler” trail Selection of stim uli governed by level of arousal. – stereo sound • Continuously overwritten Short-term memory (STM) Examples • Scratch-pad for temporary recall 212348278493202 – rapid access ~ 70m s – rapid decay ~ 200ms 0121 414 2626 – limited capacity - 7± 2 chunks HEC ATR ANU PTH ETR EET 3

Long-term memory (LTM) Long-term memory (cont.) • Repository for all our knowledge • Sem antic m em ory structure – slow access ~ 1/ 10 second – provides access to inform ation – slow decay, if any – represents relationships between bits of inform ation – huge or unlim ited capacity – supports inference • Model: semantic network • Two types – inheritance – child nodes inherit properties of – episodic – serial memory of events parent nodes – sem antic – structured memory of facts,concepts, skills – relationships between bits of inform ation explicit – supports inference through inheritance sem antic LTM derived from episodic LTM LTM - semantic network Models of LTM - Frames • I nform ation organized in data structures • Slots in structure instantiated with values for instance of data • Type–subtype relationships DOG COLLIE Fixed Fixed legs: 4 breed of: DOG type: sheepdog Default diet: carniverous Default sound: bark size: 65 cm Variable Variable size: colour colour Models of LTM - Scripts Models of LTM - Production rules Model of stereotypical information required to interpret situation Representation of procedural knowledge. Script has elements that can be instantiated with values for context Condition/ action rules Script for a visit to the vet if condition is m atched Entry conditions: dog ill Roles: vet examines then use rule to determ ine action. vet open diagnoses owner has money treats owner brings dog in Result: dog better pays owner poorer takes dog out vet richer IF dog is wagging tail Scenes: arriving at reception Props: examination table waiting in room THEN pat dog medicine examination instruments paying IF dog is growling Tracks: dog needs medicine THEN run away dog needs operation 4

LTM - Storage of information LTM - Forgetting decay • rehearsal – inform ation is lost gradually but very slowly – inform ation m oves from STM to LTM • total time hypothesis interference – new inform ation replaces old: retroactive – am ount retained proportional to rehearsal tim e interference • distribution of practice effect – old m ay interfere with new: proactive inhibition – optim ized by spreading learning over tim e so m ay not forget at all m em ory is selective … • structure, m eaning and fam iliarity … affected by em otion – can subconsciously ` choose' to – inform ation easier to rem em ber forget LTM - retrieval recall Thinking – inform ation reproduced from m em ory can be assisted by cues, e.g. categories, im agery recognition Reasoning – inform ation gives knowledge that it has been seen deduction, induction, abduction before Problem solving – less com plex than recall - inform ation is cue Deductive Reasoning Deduction (cont.) • Deduction: • When truth and logical validity clash … – derive logically necessary conclusion from given e.g. Some people are babies premises . e.g. I f it is Friday then she will go to work Some babies cry I t is Friday I nference - Som e people cry Therefore she will go to work. Correct? • Logical conclusion not necessarily true: e.g. I f it is raining then the ground is dry I t is raining • People bring world knowledge to bear Therefore the ground is dry 5