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ITEC 3230 (10)


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Information Technology
ITEC 3230
Sotirios Liaskos

INTERACTION D ESIGN 1 Understanding Users: Part I O VERVIEW What cognition is. Experiential vs. Reflexive Cognition Implications to Design Core Human Cognitive Processes Perception Attention Memory 2 W HAT GOES IN MHIND 3 E XPERIENTIAL VS . REFLECTIVE C OGNITION  Experiential  Perceive, act and react to events around us Drive a car, read a book, have a conversation.  Reflective  Involves thinking, comparing, decision making. Designing, Learning, Writing a book  Require different types of interface support Another view: 4  Automatic vs. Controlled A UTOMATIC VS . CONTROLLED C OGNITIVE P ROCESSES  Automatic  Things that we do without thinking about them  Mostly sensory-motor tasks: Driving, Cycling, Typing etc.  Fast, require minimal attention, unavailable to consciousness.  Not affected by limited capacity of brain and don’t require attention. i.e. don’t occupy brain capacity  Cannot change easily once learned. 5 AUTOMATIC VS . CONTROLLED C OGNITIVE PROCESSES Controlled Processes Non-automatic – need thinking. E.g. mental arithmetic. Require attention and conscious control. Can change relatively easily compared to automatic ones. 6 A UTOMATIC VS . CONTROLLED : MPLICATION TO D ESIGN  Goal 1: use of the interface should capitalize on automatic processes, so that users conscious thinking focuses on the actual goal they are trying to achieve.  E.g. their novel rather than how to type it in.  Goal 2: automatic processes are difficult to unlearn, thus once established should better stay as they are.  i.e. consistency 7 CORE C OGNITIVEA SPECTS Perception and recognition Attention Memory Reading, speaking and listening Problem-solving, planning reasoning and decision making, learning Most relevant to interaction design are the first three. 8 P ERCEPTION  How information is acquired from the world and is transformed into experiences.  Theories of perception:  Gestalt theory (a bit dated):  Based on the idea that groups of stimuli lead to new things that are distinct from the sum of their parts, i.e. have distinct Gestaltqualität(form-quality).  Humans have a tenancy to organize stimuli in a certain manner during perceiving.  Whenever possible, perception tends towards simplicity, symmetry and wholeness, the Prägnanz (= clear-gut, succinct, in modern German).  Famous for their stunning examples (e.g. illusions) to challenge our perception habits.  Constructivist Theory:  Our view of the world is constructed both from information in the environment and from preciously stored knowledge.  We don’t see just a replica or copy of the world as e.g. a camera.  Visual system constructs a model of the world through transforming, enhancing distorting and discarding information  Ecological Theory:  No construction but actively try to explore (use) our environment to support our activities.  Affordances important in this theory 9 G ESTALT T HEORY OF P ERCEPTION  Humans have a tenancy to organize stimuli in a certain manner during perceiving.  The parts construct new distinct wholes that have their own Gestaltqualität (form-quality) and are independent of the parts. * + * * + + * * + + * * + + * * * * * + + + + + * * + + * * + +  Humans also effortlessly distinguish between figures and backgrounds.  E.g. which shape is on top which other shape?  Which is the figure and what is the background? 10 G ESTALT PRINCIPLES Compelling principles about how humans organize perceived objects in groups. 11 C ONSTRUCTIVIST T HEORY  What do you see?  Could you see it immediately? 12  Now that you saw it can you “stop” seeing it?  Something (the context? a hint?) seems to lie between the stimuli and your C ONSTRUCTIVIST T HEORY  Constructivists claim that perception is more than just direct registration of sensations.  The end result of perception is constructed in our mind,  in-part through the observed stimulae and  in-part through an internal inference processes.  This was necessary to explain phenomena otherwise impossible to explain  e.g. perception of depth and size constancy 13 T HE “H YPOTHESIS T HEORY ”  Richard Gregory’s hypothesis theory:  Based on stimuli we receive, we build hypotheses about the world around us.  Gregory’s important observations:  Perception allows behavior that fits to object characteristics that are not sensed. E.g. we sit on a chair even if we don’t see its four legs in place.  Perceptions can be ambiguous or paradoxical (see illusions of next slide)  Perceptions can extract familiar objects from a complex unfamiliar background.  Highly unlikely objects tend to be mistaken for likely objects.  Perception may not be based to what is experienced. Take two identical photos of some, enlarge the eye pupils of one and ask experimental subject who is more attractive. 14ey will answer the one with the large pupils – though they will be unable to notice any difference between the photos. COGNITIVE LLUSIONS - COMPETING CLASSIFICATIONS OOBJECTS - PARADOXES 15 E COLOGICAL T HEORY OF P ERCEPTION  Theory of direct perception  Led by psychologist J.J. Gibson.  Questioned the constructivist unrealistic lab-oriented and controlled research.  Aimed at avoiding the dualism perceptual experience vs. objective world, but study the two together.  Basic ideas:  Perception in an evolutionary basis:  It was developed to solve animal problems (find food, avoid predators etc)  It is therefore necessary to think of perception and action in the real world together.  Invariants are properties that remain constant while stimuli change (due to movement)  Affordances are meanings of objects with respect to how they can or cannot be used.  These are perceive directly without mediating inferences the constructivist suggest.  Example:  We don’t consider the world moving when we move our eyes.  Experiments showed that our experience of relative sizes of objects…  i.e. the one that we report when asked which object is larger  …may be different from how our body relates to those objects  i.e. is we try to grip the object, our hands seem to perceive different (the correct) size differences. ECOLOGICAL THEORY Which center circle is larger? 17 E COLOGICAL THEORY (The circles have equal size actually.) While your eye mistakes the size of the center balls, your hands will not if you try to grip them! E COLOGICAL T HEORY  Invariants:  A higher order pattern or structure that is available as a source of information for the perceiver.  These patterns have properties that stay the same while stimuli change due to motion.  Transformational Invariants: When an object departs from us with a constant speed, its size appears to diminish accordingly (= invariant).  Change in the speed by which the size changes, may imply a) the object accelerated or slowed down, b) the object is actually changing size. When we more towards something, textures expand, when we move away they contract.  Structural Invariants A possible one: the ratio of an object’s height to the distance between it’s base and the horizon is invariant across all distances from the viewer. ECOLOGICALTHEORY - NVARIANTS A B If a/b = a'/b' then A and B are the same size. A FFORDANCES  “Roughly the affordances of things are what they furnish, for good or ill, that is, what they afford the observer.” (Gibson, 1971)  Affordances are the meanings which an environment has for an animal.  As such they guide behavior – they tell them what is possible and what is not.  Examples:  Tables that are stand-on-table or sit-on-table.  Objects that are graspable or throwable  Surfaces that afford supporting.  Substances that afford pouring. 21 P ERCEIVING D EPTH  Perception functions employ a wide variety of cues to understand depth.  Basic Cues include (but are not at all limited to):  Motion paralax: understand depth by moving. E.g. when you are traveling by bus or train, cer
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