Chapter 3 Human Information Processing HCI Designing Effective

Chapter 3 – Human Information Processing HCI: Designing Effective Organizational Information Systems Dov Te’eni Jane Carey

Chapter 3 – Human Information Processing Designing effective Human-Computer Interaction depends on understanding how humans process information Key aspects of Chapter 3: – HIP model – Performance is a function of speed and accuracy – Context

Chapter 3 - HIP Consider the task of editing a file using a computer which involves: – Controlled processing (versus automatic) – Goal-driven behavior (versus random) Relationship between Controlled processes and goal-driven behavior – Example: trying to catch another driver while staying below the speed limit

Figure 3. 1 Objectives and Actions in Preparing a Word Processing Document Objectives Setup File Save File Determine Layout Open Document Name the File Set top/bottom Margins Print File Actions Set Left/Right Margins Set Print Options

Steps in preparing a word-processed Step 1. Open a new file document Step 2. Assign a name Step 3. Set margins Step 4. Set printer options Step 5. Type text Step 6. Insert figures Step 7. Edit text Step 8. Add cover page Step 9. Spell check Step 10. Change font Step 11. Repeat until satisfied Step 12. Print Step 13. Save file This task is difficult to turn into an automatic process due to complexity and sub-goals and therefore will remain a controlled process.

Chapter 3. HIP What are the implications for design? – If a task is goal-driven and requires fast performance, the designer should guide the user with a sequence of actions that build toward the goal – In the case of the word processor, some default parameters can be set to minimize the work on the part of the user which in turn speeds up the task – Knowledge of HIP allows a designer to draw design implications

Chapter 3 - HIP This book will draw on several cognitive models including: GOMS (Goals, Operators, Methods, Selection Rules) by Card, Moran, Newell A rough model of Human Information Processing (HIP) – Stages of IP • • Sensation Perception Decision Response Execution

Chapter 3 – HIP The HIP view of the user – An information system that accepts inputs from the external world and produces responses directed out to the external world Inputs Outputs

Chapter 3 - HIP Figure 3. 2 Stages of Information Processing Stages of HIP Memory (Attention) Working Memory Long-term Memory Processors Perception Touch/Feeling Identification Location Cognition Translation Operation Decision Motor Translation to Action (Keyboard, Mouse)

Chapter 3 - HIP Figure 3. 2 Explanation The perceptual processor senses, detects, and accepts inputs from the external world and stores parts of the perceptions in working memory (these are visual or auditory) The cognitive processor interprets, manipulates, and makes decisions about the inputs (along with memory) The motor processor generates physical actions (such as keying and mouse clicking) based on perceptions and cognitions

Chapter 3 - HIP Figure 3. 2 Explained (cont. ) – All these parts interact with each other – The idea of performance (speed and accuracy) is introduced – HCI Designers try to implement designs that make the interface usable and increase performance – Some constraints • Working memory capacity is 7+ 2 chunks for 10 -20 seconds • Cycle time of processors around 100 milliseconds (with motor being the slowest) • Long-term memory capacity is almost unlimited,

Chapter 3 - HIP Design implications – User will notice screen changes within screen changes – User perception is limited to 7+ 2 chunks of information and will ignore part of the screen – Long-term memory retrieval will significantly degrade performance – Designs must reflect these issues Additional impacts include: motivation to use, practice, and attributes of representation (such as intensity)

Chapter 3 - HIP Perceptual Processor – Works tightly with perceptual storage – 3 principles of relevance • Input buffers of the working memory store visual and auditory images • Perceptual processor works in cycles (pulses combined to make 1 signal) • More intense signals require less time to process

Chapter 3 - HIP Cognitive Processor – Cognitive processors are automatic (fast and undemanding) or controlled (slower and demanding) – Cognitive Processors can process both images and verbal (text) information (but differently) – Cognitive processing is not always consistent over time and is content-related

3. 4 Watson and Johnson-Laird (1966) Logical Reasoning Experiment E K 4 7 $10 $30 No signature Signature

Chapter 3 - HIP Cognitive processing is not uniform and depends on: – Task requirements – User familiarity with task (automatic or controlled) – Type of information (verbal or image) – Heuristics

Chapter 3 - HIP Memory and Processing – The role of memory is critical and must be examined – Working memory • Limited capacity and retention time • Stores both images and verbal information (text) • Task complexity is related to forgetting and interference • Order is important in verbal storage • Rehearsal can increase remembrance – Working memory interacts with long-term

Chapter 3 - HIP Long-term memory – Is episodic(direct memory) or semantic(meanings) – Individual differences come into play (age for example, can negatively impact memory capacity) Organizing Memory – Schemata (high order cognitive structures such as scripts) – Metaphors (related to an already familiar concept, e. g. , desk top as a metaphor for

Chapter 3 - HIP More organizing mechanisms – Mental model – mental representation – Heuristics – short cuts or rules of thumb (e. g. , boys are more athletic than girls is a judgment by representativeness and may lead to erroneous conclusions)

Chapter 3 - HIP Principles of HIP and Memory – Different combinations of tasks and memory will trigger different cognitive processors – In simple tasks, performance (accuracy and speed) depends on heuristic processes and episodes – Complex tasks can use schemata (mental models, heuristics, metaphors) to increase performance – Unfamiliar tasks require the creation of new

Chapter 3 - HIP More principles – Heuristics is based on the salient (meaningful) task features • If the salient features provide a clear task structure then performance will be improved • Use familiar labels on screens HIP in context – Context is essential to comprehension – Immediate context (what user was doing before looking at the current screen – Distant context (in which the task occurs (like choosing the right investment portfolio)

Chapter 3 - HIP Guiding principles of context – Context must be maintained during an interactive session – Stick with one mental model or metaphor – Continuity between screens helps maintain context - Figure 3. 5 shows the Block Interaction Model of Morton, Barnard, and Hammond (1979) and helps explain how different sources of knowledge interact to affect the context of work

Figure 3. 5 Block Interaction Model by Morton, Banner, & Hammond, 1979 Knowledge of the Natural Language Knowledge of the context Knowledge of the domain Knowledge of the Version Knowledge of the process, problemsolving and mechanism Knowledge of the Problem Knowledge of the computer (documentation, software, hardware) Knowledge of the Context bound to the system Knowledge of the actions of the system

Chapter 3 - HIP Coding and Retrieving – Coding (prior to storage) – Retrieval (from memory) – Observations • The more active you are in generating information items, the better your recall • Pictures are easier to recall than words • Recall “in context” is easier than “out of context” • Complex patterns are more difficult to recall than simple • Clues stored at the time of coding make recall easier

Chapter 3 - HIP Conclusions – Models help our understanding of HIP ( – Performance is a function of cognitive management, memory, processing, attention, and comprehension – Performance is speed and accuracy – We can use schemata to organize knowledge (mental models, metaphors, heuristics) – Comprehension is sensitive to context