HCI Flashcards
Ethics
Dark patterns. Used to trick customers into buying or spending more time on a product.
Forced continuity (free 14 days and then you pay)
peak end rule
disguised ads
sneak into basket
useability and functionability (utility)
Functionality
- The functions of a given system
or product
useability
The extent to which a product can
be used by specified users to
achieve specified goals with
effectiveness, efficiency and
satisfaction in a specified context of
use.
- Ie. how ‘easy/effortless/enjoyable it
is to use a system.
uability X utility = usefulness
cogntive load examples
Attentional Load, Working Memory Load, Germane Load
- Intrinsic/extrinsic cognitive Load
hicks law
Decision time increases with number of choices.
—> Simplify
millers law
Working memory has limited capacity, but meaningful units can be constructed via chunking.
—> Facilitate chunking, use visibility, off-loading, long term recall.
jakobs law
- User transfer expectations they have build around one familiar product to another that appears similar.
- Mismatch between mental models and product increases load.
—> Use design conventions, use strong & intuitive representations,
test users to discover their mental models.
Foveal / peripheral vision:
Users can often miss information presented in their peripheral vision.
- Put info where people are looking.
- Make things ‘pop’, e.g. bold, colour.
- Use distinctive icons in case of many targets, e.g. iPhone
interface.
- Heavy artillery: Pop-ups; Sounds; Wiggling or blinking
gestalt principles
Proximity,
Similarity,
Continuity,
Closure,
Symmetry,
Figure/ground,
Common Fate.
Visual Hierarchies:
- Reading:
- Minimise need for reading.
- Make scannable text.
- Communicating what is important info, relative to other info.
fitts law
- Button size
- Button placement
Increased reaction time and error rates with smaller buttons and further away
postels law
Accept variable input from users, translating that input to meet your requirements, defining boundaries for input, and providing clear feedback to the user.
teslers law
Ensure as much as possible of the burden is lifted from the users by dealing with inherent complexity during design and development.
peak end rule
“People judge and experience largely based on how they felt at its peak and at its end, rather than on
the total sum or average of every moment of the experience.”
- We do not recall the sum of how we felt, but more so the average of an experience during its
peak moments and the end (the end relates to the ‘recency effect’).
doherty threshold
“Productivity soars when a computer and its users interact at a pace (<400 ms) that ensures that
neither has to wait on the other.”
- Operations under 400 ms are perceived as “fast”.
- Operations over 400 ms can feel annoying or frustrating to the user, make the user distracted,
make the user disinterested, make the user abandon the task.
time thresholds for users
- 0.1 second: Limit for users feeling that they are directly manipulating objects in the UI.
- 0.2–1.0 seconds: users notice the delay and often feel the computer is “working” on the command.
- 1 second: Limit for users feeling that they are freely navigating the command space .
- 10 seconds or above: Needs a progression indicator. Possibly an option to cancel the operation.
-Aesthetic-usability effect
-“Users often perceive aesthetically pleasing design as design that’s more usable.”
- An aesthetically pleasing design often lead people to believe that the design works better.
- People are more tolerant of minor usability issues when the design of a product or service is
aesthetically pleasing.
- Virtually pleasing design can mask usability problems in usability testing (minor problems, mind
you).
goals of useability testing
dentifying problems in the design of the product; uncovering opportunities to improve;
learning about the target user’s behavior and preferences.
AB testing
testing two different designs like a randomized trial
Common data types when measuring usability:
- Interaction quality (efficiency): time, attempts, ressource use.
- Measuring the performance (effectiveness): errors, error recovery, task success and
completion. - Subjective measures: perceived usability.
Moderated usability-testing session,
- Participant perform tasks, usually using one or more specific user interfaces.
- Moderator observes the participant’s behavior and listens for feedback.
- Moderator ask follow-up questions to elicit detail from the participant.
Central Concepts, test protocols and design:
Write protocol.
- The intended users, the intended use, the intended use context.
- ‘Simulated use’ tasks
- Critical use of the “Think aloud protocol”
- Alternatively ‘retrospective think aloud’ as a safer alternative.
- Alternatively using only observation and interview (Inquire with intent).
- ‘Knowledge-driven’ tasks
- Questions about things that cannot be directly tested.
- Subjective ratings
Human & AI interaction (Anthropomorphism)
the attribution of human characteristics or behaviour to the AI
