Cognitive load and mental models Flashcards
(14 cards)
What is cognitive load? What is it based on? What does it often relate to in HCI?
The amount of mental resources that is required to operate a system/product.
Based on the fact that humans have limited amount of processing power.
In HCI, cognitive load is often denoted in relation to a system, i.e. how much of user’s cognitive load that a system takes up.
What contributes to cognitive load?
Attentional load
Working memory load
Germane load
What is attentional load?
Humans cannot attend to and process all the information we are exposed to in the world simultaneously.
A certain amount of information is selected for further processing and other information is discarded (aka spotlight analogy, attentional bottleneck).
The selection is driven by two primary modes of attention:
- Top-down attention: Active, goal-directed, intentional. We attend to stimuli that seem relevant and important to us for achieving our goals (the user’s goals, not the system’s goals!)
- Bottom-up attention: Passive, stimulus-driven, incidental. Pop-out effect: When a stimulus has a feature that is not shared by other stimuli, e.g. colour, shape, movement, location.
What is working memory load?
WM is the cognitive process that enables us to temporarily hold and manipulate information while performing a task, e.g. following directions, remembering a grocery list.
Working memory relies on three systems: phonological loop (auditory and verbal information), the visuospatial sketch pad (visual and spatial information) and the central executive (coordinates the other two components)..
WM load: Limited capacity of working memory, e.g. Miller’s Law.
When do users have to rely on their working memory?
Multitasking, problem solving, information processing, navigation, decision-making.
What is germane load?
The load it takes to learn something, there is a limit for how quickly we can learn something, we don’t want systems that require a lot of learning.
What are the two types of cognitive load?
Intrinsic load: The inherently difficulty of a task or the information being processed, there will always be some amount of complexity to a task that you can’t reduce, e.g. when using an EpiPen for an allergic reaction.
Extrinsic load: The load caused by factors external to the task e.g. through poor design or overly complex interfaces.
What are two types of design standards?
External standards: Also referred to as conventions. Exposure to ways of design that is very common. All the standards that other systems/products have, you should also adhere to, e.g. the shopping cart in the right top corner, the save button.
Internal standards: Users form expectations about your product within the product’s universe, e.g. distinguish between clickable and non-clickable items in terms of colour, shapes etc, adhere to internal standards by being consistent in the design.
What is a mental model mismatch?
When the system does not adhere to internal and external standards, when they do not match.
Consequence: Increases load, need to learn individual systems, confusion, frustration.
Solutions:
- Utilise representations with strong well defined associations.
- Adhere to external standards
- Be consistent in your design (adhere to internal standards).
- Ask the users! Test the users! Pretend to be users!
Imagine and create different users
How do you avoid mental model mismatch?
- Utilise representations with strong, well-defined associations
- Using external standards
- Be consistent in your design (adhering to internal standards)
- Ask the users! Test the users! Pretend to be users!
Imagine and create different users
What is Jacob’s Law and how can you use it?
Definition: “Users spend most of their time on other sites, and they prefer your site to work the same way as all the other sites they already know”
How: Relying on mental models, top-down processing, user expectations/knowledge, external standards
What is Miller’s Law and how can you use it?
Definition: “The average person can keep only 7(±2) items in their WM”. Yet! The point is not the number but the idea that WM is limited, and organising information into meaningful chunks can improve memory.
How:
- Facilitate chunking
- Visibility (essential options visible)
- Build on existing mental models
- Off-loading (e.g. make support for note-taking that allows users to save information
What is Hick’s Law?
Definition: “The time it takes to make a decision increases with the number and complexity of choices available”. Relates to attentional load, working memory and germane load.
Examples: Remote controls, google search (filtering options after searching), onboarding
How:
a. Minimise choices (decreases decision time)
b. Break complex tasks into smaller steps
c. Avoid overwhelming - highlight recommended options
d. Use progressive onboarding
e. Avoid visual clutter, e.g. through redundant links, irrelevant images
f. Offload tasks - can we present information differently, e.g. a picture/icon instead of text
g. Add contextual info, e.g. labels to icons
But! Be careful not to oversimplify (e.g. too abstract icons)
What is a mental model?
The set of expectations and beliefs that a user has about a system and how it works. Helps the user predict how a system will work.
We form a mental model based on past experiences and then we apply that model to new situations where we encounter similar systems.
Examples: Online shopping that resembles physical shopping. Back button. Adjusting the car seat.
