Chapter 3: Information Processing

Transcription

1 SENG 5334: Human Factors Engineering & INDH 5931: Research Topics in IH/Safety Chapter 3: Information Processing By: Magdy Akladios, PhD, PE, CSP, CPE, CSHM 1 A Model of Information Processing Def: A model is an abstract representation of a system or process Models can be: Mathematical Physical Structural Verbal 2 Structural Model By: Dr. Magdy Akladios 1

2 Simple Perception Complex Perception 1. Perception 4 Sensory Input 1. Sensory receptors transduce external energy in a limited spectrum into nerve impulses. 2. Sensory information is actively organized by perceptual processes (or levels of perception, depending on the stimulus) 3. An internal representation of our external world is then created. 4. Perceptual organization occurs in a 'top-down' manner to impose order on sensory 5 information Perceptual Processes 1. Detection: Determination of whether a stimulus is present or absent. Not a foolproof process. 2. False alarm: Report that stimulus is present when absent. 3. Miss: Report that stimulus is absent when present. 4. Recognition: Noticeable familiarity without the ability to label the stimulus. 5. Identification and Recognition: Full identification of the stimulus (recognition + labeling). 6 By: Dr. Magdy Akladios 2

3 Signal Detection Theory 7 Signal-Detection Theory (SDT) Applies where there are 2 discrete states (signal or no signal) All decisions are based on probabilistic information Ease of decision making depends upon the: Signal : Noise ratio Strength of the Signal 8 Signals and Noise Signal: Relevant input event Noise: Background nervous activity (internally) and/or (externally) irrelevant inputs. Noise interferes with the detection of a signal 9 By: Dr. Magdy Akladios 3

4 4 Possible Outcomes for 2 States of Reality 1. Hit: Saying there is a signal when there is one 2. False Alarm: Saying there is a signal when there is none. 3. Miss: Saying there is no signal when there is one. 4. Correct rejection: Saying there is no signal where there is none. 10 SDT No Signal Signal Reject Correct Rejection Miss Accept False Alarm Hit 11 SDT - Response Criterion Response criterion: This is a subjective criterion level that produces "signal present response when exceeded. Represented by ß (beta) = ratio of Signal : Noise 12 By: Dr. Magdy Akladios 4

5 13 14 Risky Conservative Criterion Response 15 By: Dr. Magdy Akladios 5

6 16 How to influence Response 1. Setting the likelihood of observing a signal (Signal probability). i.e., high probability = low criterion. 2. The Costs associated w/the 4 possible outcomes: Criterion increases (shifts to the RIGHT, or becomes more CONSERVATIVE) as costs of a FALSE ALARM increase (e.g. Nuclear War). Criterion decreases (shifts to the LEFT, or becomes more RISKY) costs of a MISS increase (e.g. Cancer)--As a result, benefits of a HIT also increase 17 Sensitivity Sensitivity is the keenness or resolution of the sensory system In SDT it is called d' (d-prime) and is the distance between the signal and noise curve peaks of the two distributions d' is expressed in units of Standard Deviations d' ranges between 0.5 and 2.0 The greater this distance the easier it is to correctly detect the signal 18 By: Dr. Magdy Akladios 6

7 2. Human Memory 19 What is Memory? Memory is a collection of systems for the Storage and Recall of information (personal experiences, emotions, facts, procedures, skills and habits). Memory systems have limited capacities Memories can be self-created (false memories) 20 The Goal of Memory The goal of memory is to leave you with a coherent story of what happened 21 By: Dr. Magdy Akladios 7

8 Human Memory Systems Functionally, human memory systems can be grouped into three systems: 1. Short-Term Sensory Storage (STSS) 2. Working Memory (Short-term memory - STM) 3. Long-Term Memory (LTM) Short-Term Sensory Storage Short term memory provides a temporary storage of stimulus after the stimulus has ceased Automatic, fast (< 1 second), temporary storage for each sensory channel. Auditory system - echoic memory Visual system - iconic memory 23 Short Term Memory Examples 24 By: Dr. Magdy Akladios 8

9 Write down the following letters after the screen is turned 25 U M By: Dr. Magdy Akladios 9

10 T Z L D K X C E J O 30 By: Dr. Magdy Akladios 10

11 31 A V C Y I S E H By: Dr. Magdy Akladios 11

12 L B F Q R P M A U X Z Q E C T B U M O N R U 36 By: Dr. Magdy Akladios 12

13 37 Answers 1. U M 2. T Z L D 3. K X C E J O 4. A V C Y I S E H 5. L B F Q R P M A U X 6. Z Q E C T B U M O N R U 38 For the following picture, write down the items after the screen is turned 39 By: Dr. Magdy Akladios 13

14 40 41 Answers BUTTERFLY ICECREAM RAINBOW CHAIR PHONE LOCK GUITAR AIRPLANE COMPUTER PLANT BIRTHDAY CAKE SLICE PENCIL CONE HOUSE WALL CLOCK KYTE SCISSORS LIGHT BULB APPLE GLOBE HAMMER 42 By: Dr. Magdy Akladios 14

15 2. Working Memory Limited capacity, temporary storage system. Variable but limited duration system (15-~30 sec. -- a few minutes). Takes ~38ms to search for items in working memory Time of search is linear with amount stored Effectiveness decreases with ageing Working memory can be disrupted by interference and time decay effects. 43 Working Memory Working memory requires uninterrupted rehearsal for maximum effect: Maintenance rehearsal - helps to maintain items in short-term storage by repetition (e.g. repeating a phone number) Integrative rehearsal helps the transfer of items from STM to LTM (takes ~ 30 minutes). Contents of STM are compared with LTM to determine what should be stored types of codes for Working Memory 1. Visual 2. Phonetic 3. Semantic 45 By: Dr. Magdy Akladios 15

16 DOG 46 Capacity of Working Memory Example 47 J T N L 48 By: Dr. Magdy Akladios 16

17 Count backwards by 3s from Now, do you remember the 4 letters presented earlier? 50 Chunking (increases the capacity of working memory) Capacity is approximately 7 ± 2 "chunks". A Chunk" is an item of information. Chunks are not single stimuli such as single letters or numbers, but they can be larger units such as words, phrase, etc. Chunked information is easier to learn and remember (phone #'s, SS#, car plates, credit card #'s). 51 By: Dr. Magdy Akladios 17

18 Example: C.A.T.D.O.G.R.A.T. CAT DOG RAT 52 Example: IB MJF KTV IBM JFK TV Long-Term Memory (LTM) LTM items can persist for decades LTM poorest in young (<3 years) and old people Recognition and Recall use different brain regions 54 By: Dr. Magdy Akladios 18

19 Long-term Memory (LTM) LTM Involves item transfer from working memory: Procedural memory: how to perform a sequence of actions. Episodic memory: when and where an event occurred. Personal experience memory. Includes flashbulb memory. Semantic memory: verbal and numeric codes and their meaning. Memory for facts Mnemonics Mnemonics can aid LTM performance 57 By: Dr. Magdy Akladios 19

20 Example Name the great lakes in the U.S.A. 58 Answer HOMES: 1. Huron 2. Ontario 3. Michigan 4. Erie 5. Superior 59 Neural Basis LTM is based in the brain's neural networks These networks are composed of neural cells, called Neurons. It is estimated that there are over 100 billion neurons in the brain which can form many trillions of potential interconnections. These neurons form complex webs that enable the brain to perform as an extremely powerful, parallel processor. 60 By: Dr. Magdy Akladios 20

21 Synapses Neurons communicate across junctions, called synapses, by electrochemical means. There are approximately one million trillion synapses. Synapses increase in efficiency to facilitate the transmission of nerve impulses as learning occurs. 61 Changing Minds!! Our brain alters the strength of existing neural connections, alters the information contained in neural webs, and/or produces new neural connections between neurons. This means that our brains are constantly changing throughout our lifetime. 62 Brain Power The more specific neural pathways are used the stronger they become and the more likely they will be used again. As multiple pathways are simultaneously excited, new neural pathways are created which increases the brain's ability to learn. HENCE: The more we recall and use specific memories or information the easier recall of the information becomes. 63 By: Dr. Magdy Akladios 21

22 Retrieval LTM includes both: Recent information (which can be fragile), and Information that has been consolidated and in store for some time 64 The process of consolidation is thought to take place in the hippocampus which creates the memory traces and transfers the memories to other parts of the cerebral cortex for long-term store. 65 Sleep, particularly Rapid Eye Movement (REM) phases, plays an important part in consolidation. The retrieval of information from long-term memory falls into one of two categories: Recognition Recall 66 By: Dr. Magdy Akladios 22

23 Recognition Recognition is the identification of items based on prior learning and LTM storage. It can be thought of as a "pattern" match of the item (or person) with a pattern in memory. We are much better at recognition than recall. We can recognize with 90% accuracy hundreds of items a week or more after presentation. Recognition can be likened to a Multiple Choice" question on an exam. 67 Recall Recall is more difficult than recognition because the item (or person) must first be recognized and then specific, associated information found and retrieved from long-term memory. Recall is more like a fill-in-the-blank test. 68 Forgetting All of us have experienced forgetting. Forgetting can be particularly frustrating when attempting to access information that we know we have learned, have accessed before, need immediately--but cannot remember. Forgetting can be due to a problem with: Encoding Storage Retrieval, or A combination of these factors. 69 By: Dr. Magdy Akladios 23

24 3. Decision Making 75 People Decision Making is Biased because: 1. People put more emphasis on early information 2. People do not extract information as they optimally should 3. People do not adequately assess subjective alternatives 4. People become more confident in their decisions with more information, not necessarily accurate 5. People tend to seek more information than they can actually digest 6. People treat all information as if it were equally reliable 76 People Decision Making is Biased because: Cont: 7. People can not entertain more than a few hypothesis at a time 8. People tend to focus on only a few critical attributes at a time 9. People seek information that confirms the chosen course of action 10. A potential loss is given more weight than a gain of the same amount 11. People believe that mildly positive outcomes are more likely than mildly negative outcomes 12. People believe that highly negative outcomes are less likely than mildly negative outcomes 77 By: Dr. Magdy Akladios 24

25 Workload Analysis NASA-TLX - The NASA Task Load Index (TLX) incorporates six subscales: mental demand, physical demand, temporal demand, performance, effort level, and frustration level. SWAT - The Subjective Workload Assessment Techniques (SWAT) has subscales assessing loads for time, mental effort, and psychological stress Attention Selective Attention Eg: A quarter back scanning for an opening Requires scanning of several channels to perform a single task Which is better: One dial with 25 signals/min 5 Dials with 5 signals/min each? 80 By: Dr. Magdy Akladios 25

26 2. Focused Attention Reading a book while there are other distractions going on at the same time Best if you can physically separate two sources of information Example: for auditory signals, make the channels distinctly different (male vs. female) Divided Attention Doing two things at the same time Sustained Attention Sustained attention for a long time without rest Sustained attention is also called Monitoring, or Vigilance 83 By: Dr. Magdy Akladios 26

27 How to Improve Vigilance 1. Provide appropriate work-rest schedules and task variations 2. Make the signal larger, more intense, longer duration 3. Reduce uncertainty as to when the signal will appear 4. Inject artificial signals and provide feedback to the operator 5. Provide adequate training 6. Improve motivation by emphasizing the importance of the task 7. Reduce the rate of stimuli 8. Maintain environmental factors at optimal levels 84 Age and Information Processing 85 Aging and Information Processing 1. Slower performance (retrieval/processing of information) 2. Increased disruption of working memory 3. Difficulty in searching for material in long-term memory 4. Difficulty in dealing with incompatibility 5. Decrements in perceptual encoding of stimuli 86 By: Dr. Magdy Akladios 27

28 What to do to help older people 1. Strengthen signals displayed 2. Design controls and displays to reduce irrelevant details (noise) 3. Maintain a high level of compatibility 4. Reduce time-sharing demands 5. Provide time between signal and required response 6. Allow more time/practice to better learn the material 87 By: Dr. Magdy Akladios 28