The Papers Presented � Perceptual and Interpretative Properties of Motion for Information Visualization, Lyn Bartram, Technical Report PERCEPTION CMPT-TR-1997-15, School of Computing Science, Simon Fraser University, 1997 � To See or Not to See: The Need for Attention to Perceive Changes in Scenes, Rensink RA, O'Regan JK, and Clark JJ. Psychological Science , 8:368-373, 1997 By Juan Gabriel Estrada Alvarez � Internal vs. External Information in Visual Perception Ronald A. Rensink. Proc. 2nd Int. Symposium on Smart Graphics, pp 63-70, 2002 Perceptual and Interpretative Properties The Papers Presented of Motion for Information Visualization � Perceptual and Interpretative Properties of Motion for � (Static) Graphical representations (eg. Shape, Information Visualization, Lyn Bartram, Technical Report symbols, size, colour, position) are very effective CMPT-TR-1997-15, School of Computing Science, in infovis because they exploit the preattentive Simon Fraser University, 1997 process of the human visual system when used � To See or Not to See: The Need for Attention to well Perceive Changes in Scenes, Rensink RA, O'Regan JK, � Nonetheless, when the perceptual capacity to and Clark JJ. Psychological Science , 8:368-373, 1997 assimilate all the combinations of codes and � Internal vs. External Information in Visual Perception Ronald A. Rensink. Proc. 2nd Int. Symposium on Smart dimensions is exceeded, more cognitive effort is Graphics, pp 63-70, 2002 required Introduction The Bandwidth Problem � Complex systems such as those used in � Data acquisition capabilities of control systems supervisory control and data acquisition are have increased: the operator’s role has evolved characterized by large volumes of dynamic from low-level manual control to high-level information which don’t reasonably fit into a management and supervision single display � Thus the complexity of the underlying � The interface of such systems should not only information space and the volume of data used display the data reasonably, they should also: in the operator’s tasks has “ballooned” � Signal the user when important changes take place � Indicate clearly when data are associated or related in � The display capacity can be increased, but there some way are limits in the user’s perceptual capacity 1
Bandwidth Problem Insufficient Information � Most common display dimensions for coding value and state � Current systems are deficient in 3 areas: are colour, position and size. Symbols and icons are heavily used � Effective representation of how the system changes; � But the number of symbols which can be perceptually decoded is the most crucial requirement to understanding a limited to about 33 (process and network displays use much larger dynamic system. This is too difficult with static symbol sets) � Similarly, color is over-used in most systems (fully saturated hue is graphical representations the dominant code, when we can distinguish only 7-10 hues) � Integration of data across displays; “inviting all the � Most common indication of fault (alarm) is blinking or flashing the relevant display element right pieces of info to the party” � Most displays are densely populated and the subscribed display � Representation of data relationships; no well- dimensions over-used. Thus flashing or blinking causes data overload established techniques to display the dynamic � Since the interfaces of these complex systems suffer from the relations between elements (association, above, we get too much direct data and not enough dependencies, sequence/order, causality) “information” Perceptual Principles for Visualization � Proximity compatibility: depends on two dimensions � Perceptual proximity: how close together 2 display channels are Issues in the design of complex in the user’s perceptual space (i.e. how similar they are) � Processing proximity: the extent to which sources are used as part of the same task system displays � Emergent Features are useful for integrative tasks � “properties inherent in the relations between raw data encoding which serve as a direct cue for an integration task which would otherwise require computation or comparison of the individual data values.” � Directed Attention � The user should be able to pick up signals without losing track of current activities � Such a signal should carry enough partial info for the user to decide whether to shift attention to the signaled area � The representation should be processed with no cognitive effort Ecological Approach The Design Challenge � Ecological Perception: “We perceive our � Two directions must be followed to minimize info environment directly as ecological entities and overload in the user interfaces to complex movement” systems: � The composition and layout of objects in the � Explore new perceptually effective ecological environment constitute what they can afford to the observer representations to increase info dimensionality (and hence interface bandwidth) � Ecological Interface Design: represent higher- order function, state and behaviour information � Determine whether these new coding dimensions can of a system as task-relevant variables integrated extend the integrative effect across displays and over lower-level system data representations separated by space and time 2
3 Reasons to believe in Motion 3 Reasons to believe in Motion 1. Perceptually efficient at a low level 2. It has a wide interpretative scope “Motion is cognitively and ecologically rich… � � Motion perception is a preattentive process, motions are ecological events to do with the and it degrades less than spatial acuity or changes in the layout and formation of objects and colour perception in the “periphery” surfaces around us” � Human visual system is good at tracking Motion affords behaviour and change � and predicting movement (“intuitive � Drama, dance and music map very complex physics”) emotions on to gestures and movement � We use motion to derive structure, animacy 3. Motion is under-used and thus available as a and emotion “channel” of information Motion as a Display Dimension Motion as Meaning � � Roughly classify the perceptual and interpretative “What are the salient perceptual features of characteristics of movement that may convey meaning motion? What are the emergent and as giving insight into behavioural properties? Can they be “tuned” to � Basic Motion: relating to perceptual properties (basic parameters influence/alter its meaning?” that affect the meaning somehow e.g. velocity, frequency, etc.) � Interpretative Motion: the type of motion produced by basic � “What do motions “mean”? Is there any motion parameters together represents the behaviour and meaning (state) of the system (a complex motion may be a inherent tendency to assign any semantic combination of several types) association to types of motion? Can motion � Compound Motion: a combination of two or more movement sequences which elicits the effect of a single perceptual and semantics be divorced from those of the interpretative event (e.g. an event that causes another event to moving object?” be triggered - causality) The prototype taxonomy Questions to be answered � “What is the “coding granularity” of motion? How many different motions can be used together for coding without interfering with each other? What other modalities reinforce/countermand the effects of motion?” � “What can motion afford in the virtual ecology of the complex system interface, and how can we best exploit these affordances?” 3
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