Human Capabilities; People; Technology HCI and Cognitive Frameworks Perception Attention / Memory Knowledge / Conceptual Models Learning

Introduction –

Human Capabilities:

Lecture 1 Overview

Human Capabilities; People; Technology

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HCI and Cognitive Frameworks

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Perception

■

Attention / Memory

■

Knowledge / Conceptual Models

■

Learning

Cognitive Computing and its applications in HCI

Human Computer Interaction

Preece, J. Addison & Wesley

What is HCI?

HUMAN MACHINE

GOALS

functions actions

Central Aim and Approach of HCI

Approach:

User-Centred

■ Users should not have to adapt to the interface

■ Interface should be intuitive/natural to learn/use.

“Talking to users is not a luxury, it’s a necessity”

Aim:

To optimise performance of

The Parts of

User Interface Development

Development of the user interface

Development of the interaction component COGNITION Development of the interface software e.g. PRINCIPLES Constructional Behavioural

Poor interface may cause:

❖ Increased mistakes in data entry / system operation

❖ Inaccessible functionality

❖ User frustration: low productivity and/or under

utilisation

❖ System failure because of user rejection

Nearly half of entire software development effort relates to the user interface.

Cognitive scientists analyse

“What the mind does…”

Investigate mechanisms/processes from which mental phenomena emerge and nature/structure of human knowledge

Mental phenomena such as……

■ Perceiving – learning – remembering

■ Controlling actions

■ Thinking - Emotion

■ Planning – Imagining – Creating

■ Understanding language and others

■ Communicating with others

Model Human Processor

■ Perception (Visual)

■ Knowledge

■ Attention

■ Language etc

The Model Human Processor

■ Brain viewed as three interacting subsystems

(each with memory store and processor)

■ Perceptual system (storage of signals from senses

e.g. images, sounds; brief time memory = sensory register)

■ Cognitive system (‘think’, analyse, recall from LTM; storage

in STM/working memory)

■ Motor system (called on when physical response is required

– transmit signals to muscles)

Perception

–

Why do things look the way they do?

Perception is

translation of physical world

into pattern of neural activity

that can be used by brain

to guide behavior.

‘Perceptual organisation’

Understanding of how we put

together the basic features

(edges, colours, motion, depth etc.)

Perception in Computing

Fundamental for HCI

■ Perceive info presented at/through interface

■ Theories of perception influence interface design

■ Present info in easily understandable/unambiguous

manner i.e. user-centred

Why Study Perception ?

Practical reasons:

■ Identify/correct environmental hazards; ■ Design devices

■ to optimize perceptual performance; ■ for people with perceptual impairments.

Perception and pleasure:

■ Visual art/music/gourmet cuisine engage sensory system in ways that we find pleasurable

■ Understanding perception allows us to heighten our sensory experiences.

Visual Perception:

Perceptual world can be different from real world!

Human system is capable of perceiving objects

■ brightest of sunlight/darkest of night

■ rapidly moving objects/rapidly decaying events

Human system cannot perceive

■ Bullet being shot / Plant growing / Infrared light

So we can obtain info from displays

• which vary in quality, size and other characteristics

• but not with uniform efficiency across whole

Vision application:

Pedestrian finding

■ many pedestrians look like lollipops (hands at

sides, torso wider than legs) most of the time

■ classify image regions, searching over scales

■ But what are features?

Vision application: Pedestrian finding

Perception =

‘

The way we see

’

:

Constructivist

• Intervention of representations/memories

• View world by constructions from info in

environment / previously stored knowledge

• Don’t see replica/copy of world but model created by

transforming, enhancing, distorting and discarding info / retinal images.

• Effect = constant view of world

Sensitivity to Colour Combinations

(3 Cones sensitivity to colour/light of equal intensity)

Colour Pairs – avoid extremes

Extreme Colour Pairs

Saturated Colour Pairs

Causes of colour and their

appearance

Sensation of color is caused by brain.

■ Some ways to get this sensation include pressure on eyelids,

dreaming, hallucinations, etc. Main way to get it is response of visual system to presence/absence of light at various wavelengths.

Color appearance is strongly affected by (at least):

■ other nearby colors,

■ adaptation to previous views ■ “state of mind”

Background Colour and

Apparent Brightness and Size

Colour selection can effect presentation of info

■ Colours look brighter and larger against black

STROOP EFFECT

(Colour naming is affected by more than just physics)

Read ALOUD and FAST 1) colour names of XXXs

2) colour names of RHS (word/colour same) 3) colours of RHS

Colour Appearance and

Surrounding Colours (1)

Which is most appealing?

Why?

Colour Appearance and

Surrounding Colours (2)

Grey figures ARE same

Contrasting backgrounds

affect perception of colours

Guidelines for Use of Colour in Applications:

Visual Density & Balance

■

How `tightly packed’ text is on screen

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Measure of amount of ‘White Space’ in relation

to amount of text

■

High density = lots of text and little white

space

■ More difficult to read

People perceive patterns/structures in displays

Visual and Other Coding

■ Differing Intensity (brightness, lightness)

■ Shape e.g. box frame (recognise/pickout)

■ Colour and/or shading

■ Underlining (not recommended in printed text – can

slow reading)

■ Character

size

font

Causes of color and their

appearance

The sensation of color is caused by the brain.

Color appearance is strongly affected by (at

least):

■ other nearby colors,

■ adaptation to previous views

Colour

Attracts

Eye

:

■ Old PCs didn’t have power/RAM to use colour; Falling costs

■ Colour on computer screens?

■ Aesthetically pleasing (prefer to Black/White)

■ Improve human efficiency by adding extra coding dimension

■ Easier to find / distinguish e.g. search for ‘targets’ - characters, words etc ■ Memory better

■ Provides (useful) redundant coding e.g. Standard background colour for

screens

■ Limited advantage over monochrome display – only add

colour to enhance interface – should function without it

Value of Colour in

(Mainly) Text Screens

■ Help user search/distinguish between items ■ Used to segment screen into related info

■ Relates separate fields of info

■ i.e. same type = same colour

■ Used to Categorise e.g.

■ Actual and projected figures ■ More or less recent data

■ Caption or data field

■ User or computer provided data

Guidelines for Use of Colour -

Screens Containing Mainly Text (1)

■ Don’t use too many colours (<4/5)

■ Use colour coding to support user’s task (not hinder)

■ Identify similar instances

■ Exceptional instances e.g. warnings (bright to emphasise) ■ Common coding scheme

■ Green - normal or OK ■ Orange - caution

■ Red – problem/danger/hot

■ No universal/multicultural interpretations of colour

■ in chemical plant, red colour might just mean hot

‘Optimal Colour Combinations’ chart

Lecture 1: Review

■

HCI and Cognitive Frameworks

■

Perception

■

Attention / Memory

■

Knowledge / Conceptual Models

■

Learning