Exploring Preattentive Attributes

Examples of Preattentive Attributes (some "pop out" more than others)
Filled (design à la Ware)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	I find the filled one has a strong pop-out effect, even when there are a healthy number of filled ones.
Not Filled (design à la Ware)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	The pop-out effect, while noticeable, is not as strong as that for the Filled case.
Hue/Color	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	Hue/color is one of the "obvious" attributes - ", as long as the colors to be noticed are sufficiently different from the others.
Intensity/Lightness (design à la Few)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	The effectiveness of intensity/lightness can be fairly sensitive to the degree of lightness.
Sharpness (design à la Ware)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This is based on Chapter 2 of Ware. There is a definite difference in the degree of pop-out effect depending on the color of the targets.
Surrounding Color (design à la Ware)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This is hard not to notice. It can also be used to identify groups (see Figure 6.10 in A. Cairo's The Functional Art).
Added Marks On Lines (design à la Few)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	S. Few includes this as one of the preattentive attributes "most applicable to data presentation" in his Tapping the Power of Visual Perception.
Added Marks on Shapes (design à la Ware)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This is in the html for the description of added marks on shape (in section right before Motion). There could be lots of stuff here to say and link to.
Closure (design à la Healey)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This is the html for the description of closure. There could be lots of stuff here to say and link to.
Curvature I (design à la Healey, Ware)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This is the html for the description of curvature. There could be lots of stuff here to say and link to.
Curvature II (design à la Few)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This is the html for the description of curvature. There could be lots of stuff here to say and link to.
Elongation (design à la Ware)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This attribute is included in Chapter 2 of Ware.
Enclosure (design à la Few, Ware)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This is the html for the description of enclosure. There could be lots of stuff here to say and link to.
Intersection (design à la Healey)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This is the html for the description of intersection. There could be lots of stuff here to say and link to.
Joined Lines (design à la Ware)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This is the html for the description of intersection. There could be lots of stuff here to say and link to.
Line Length (design à la Few)	Number Targets 0 1 2 3 4 5 6 7	This is the html for the description of line length. There could be lots of stuff here to say and link to.
Line Width (design à la Few)	Number Targets 0 1 2 3 4 5 6 7 Line Width 1 2 3 4 5 6	This is the html for the description of line length. There could be lots of stuff here to say and link to.
Misalignment (design à la Ware)	Number Targets 0 1 2 3 4 5 6 7 10 20 Off By: 0 1 2 3 4 5 6	This is the html for the description of misalignment. There could be lots of stuff here to say and link to.
Orientation (design à la Few)	Number Targets 0 1 2 3 4 5 6 7 10 20	This is the html for the description of orientation. There could be lots of stuff here to say and link to.
Shape	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	I find that the pop-out effect for shape is more sensitive to the size of the shapes. Also, it is easier if the target has corners (like the square here) and the distractors don't.
Sharp Vertex (design à la Ware)	Number Shapes 20 40 80	This is based on Chapter 2 of Ware. While the pop-out effect is there in this case, I am a little unclear as to why this specific case is pointed out in Ware's book- I couldn find a it in the two references Ware mentions.
Size (design à la Few)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	Size has to be one of the strongest preattentive attributes - even with many targets the pop-out effect is strong.
Terminators (design à la Healey)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This is the html for the description of terminators. There could be lots of stuff here to say and link to.
3D Depth Cue (design à la Healey)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This based on C. Healey's Perception in Visualization.
Cast Shadow (design à la Ware)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This is based on Chapter 2 of Ware.
Convex and Concave (design à la Ware)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This is based on Chapter 2 of Ware - there is a strong pop-out effect. This is implemented by using a shifted radial gradient on the circles.
Lighting Direction (design à la Healey)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This based on C. Healey's Perception in Visualization.
Blinking	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	This is mentioned in both Chapter 2 of Ware and C. Healey's Perception in Visualization. While there is obviously a risk of irritation with this attribute, it is hard to deny that it is not an effective way to attract notice.
Direction of Motion (design à la Healey)		Here, "direction of motion" refers to preattentively detecting different of one objects movement relative to the movement of other moving elements around it.
Emerge (mentioned in Ware)		Wait a few seconds for it to appear from one of the sides (click New for it to come from a different location and at a different time) ... this kind of "interrupt" is mentioned in Chapter 2 of Ware.
Rotation (subjective)	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	I have not seen rotation explicitly called out anywhere (although I am sure it has been), but wanted to include it because of its fairly strong pop-out effect when the object being rotated has edges.
Twitch (subjective, akin to Ware's "jiggle")	Number Targets 0 1 2 3 4 5 6 7 10 20 Number Shapes 20 40 80	In the section on Motion in Chapter 2 of Ware, he notes that "It is hard to resist looking at an icon jiggling on a web page, which is exactly why moving icons can be irritating". When it comes something more akin to an alerting twitch, however, I think the risk of irritation is lower.
Velocity (design à la Healey)		This is the html for the description of velocity. There could be lots of stuff here to say and link to.
Density (design à la Healey)	Number Targets 0 1 2 3 4 5 6 7 10 20	This is the html for the description of density. There could be lots of stuff here to say and link to.
Detect Boundary (design à la Healey)		Healey discusses boundary detection as being one of the preattentive attributes, where we can detect the direction of the boundary when it is defined some unique feature (he references the work of ANne Treisman and others).

C. Ware, Visual Thinking: for Design	The features that pop out are hardwired in the brain, not learned. Colin Ware, in Visual Thinking: for Design (Kindle Location 750) Pop-out effects depend on the relationship of a visual search target to the other objects that surround it. If that target is distinct in some feature channel of the primary visual cortex we can program an eye movement so that it becomes the center of fixation. Colin Ware, in Visual Thinking: for Design (Kindle Location 682-684) What makes a feature distinct is that it differs from the surrounding feature in terms of the signal it provides to the low-level feature-processing mechanisms of the primary visual cortex. Colin Ware, in Visual Thinking: for Design (Kindle Location 712-714)
C.G. Healey, Perception in Visualization	Typically, tasks that can be performed on large multi-element displays in less than 200 to 250 milliseconds (msec) are considered preattentive. Eye movements take at least 200 msec to initiate, and random locations of the elements in the display ensure that attention cannot be prefocused on any particular location, yet viewers report that these tasks can be completed with very little effort. This suggests that certain information in the display is processed in parallel by the low-level visual system. C. Healey, in Perception in Visualization
A. Cairo, The Functional Art: An introduction to information graphics and visualization	If you know what tricks and shortcuts the brain uses to make sense of the information gathered from the senses, you can use that knowledge to your advantage. ...The ability to anticipate what the brain wants to do can greatly improve your information graphics and visualizations. Alberto Cairo, in The Functional Art: An introduction to information graphics and visualization (Voices That Matter) (Kindle Locations 1624-1626)
S. Few, Tapping the Power of Visual Perception	...if you want to visually encode information in a manner that can be perceived instantly and easily by your readers ... you should visually encode the data using preattentive attributes, and if you want some of the data to stand out from the rest, you should encode it using different preattentive attributes. S. Few
C. Nussbaumer, garage sale signs and data viz: the power of preattentive attributes	... if you use preattentive attributes well (especially color), your audience can't help but focus on the important part(s) of the message. By playing on their iconic memory, you're making it so they are seeing what you want them to see before they even know they are seeing it. Which is a crazy powerful thing. C. Nussbaumer
G. Odds, The science behind data visualisation	... to maximise the power and efficacy of a visualisation, we should seek to encode as much information as possible in the pre-attentive features perceived during bottom-up processing. G. Odds