1. User Psychology ITKP103 Human Being and Information System http://www.cs.jyu.fi/ky/kurssit/itkp103/index.html Sacha Helfenstein sh@cc.jyu.fi Lectures 28.10, 2.11., and 4.11.2005

2. Perception Perception ≠ mental copy of stimuli Perception is the process and product of actively selecting and organizing sensory information. Limits and Laws (e.g., contrasts, 3D, Faces, Gestalt Laws

3. Limits of Perception: Light Light impression: Wavelength of ca. 380 nm to 740 nm Color spectrum: Differentiation of ca. 10 mio colors redgreenbluered+greengreen+bluered+bluered+green+bluezero light redgreenbluered+greengreen+bluered+bluered+green+bluezero light redgreenbluered+greengreen+bluered+bluered+green+bluezero light

4. Wavelenght Sensitivity of Cones

5. The Opponent Process Theory Cells are connected so as to place sensations of: red in opposition to green blue in opposition to yellow black in opposition to white (Hering, 1878; Hurvich & Jamison, 1957)

6. Psychophysics of Sensation Weber (1846): Just noticable difference (JND, ∆I) = k I (stimuli-specific) Fechner (1860): Sensation (S) = K log I

7. Limits of Perception: Sound Sound impression: Frequencies between ca. 10Hz and 20kHz, with frequencies around 3500Hz appearing the loudest Volume: Sound pressures from 0dB - 85bB (damaging level) – 130dB (pain level) - ?

10. Gestalt Laws Proximity Closure & Figure-Ground Similarity Common Fate & Continuity Symmetry In search of the „Good Figure“ „The whole is different from the sum of the stimuli“ e.g., Koffka (1935)

11. Application SimilarityContinuity e.g., Music Closure Proximity

12. Perception and Attention Factors influencing visual representation, e.g.,: –Visual saliency (e.g., pop-out, contrasts, familiar schemata) –Cognitive saliency (e.g., gist, consistency, context) –Principles of perception (e.g., Gestalt laws) –Task goal Key properties of attention: –Division and Selection –Control vs. Automation

13. Stroop Effect (1935) Punainen Violetti Oranssi Vihreä Valkoinen Sininen Violetti Keltainen Musta Vihreä Sininen Oranssi Valkoinen Hattu Kortti Ranska Kone Kenkä Veitsi Punainen Violetti Oranssi Vihreä Valkoinen Sininen

14. Important psychological concepts Capacity –limitations of information processing Selectivity –focus of information processing Division –parallel processing Construction –organization of information... –... into meaningful wholes

15. Users‘ Learning and Thinking Repetitio mater studiorum est Consistency and Interference Recognition is easier than recall Learning and thinking is context dependent Law of Experience -> Transfer of Learning  Familiarity  Affordance  Metaphors (metapherein = to transfer)