> different design decisions. Frutiger wanted a vibrant face for signage. Twombly and Slimbach I think were going for a more calm text face.

Interesting, as I was reading the first part of the post, I was wondering if this edge effect thing (I have not read Unger, yet) applied to all type, or only to display sizes. It just seems to me that an effect of this kind cannot be processed on text sized type.

Am I on target there?

I would have thought it was the other way round. I think that the edge effect only affects a narrow band around the edge; at display sizes, you mostly see what’s there, but at text sizes, the edge is relatively larger, and it’s small enough for your eyes (really your brain) to deceive you.

I hope that makes sense.

I think the edge effect takes place at every size, though there may be some scale effect. I haven’t yet read the literature. It is also interesting that more is going on in the interaction of black and white than the edge effect alone—or at least the edge effect is complex.

There is an illusion known as the Hermann grid illusion, which you can see here:

This was explained by the ’lateral inhibition’ and the edge effect, but that explanation as the whole story has been refuted by a version with wavy lines, in which the phantom grays at the intersections disappear.

Evidently, it makes a difference whether lines are straight, and whether they are horizontal and vertical etc.

Though it works at text and display sizes, the question is where it is appropriate. In another discussion, I questioned whether the ’picket fence’ effect was something always to be avoided in type design. Nick Shinn rightly pointed out that in display type particularly you might want ’dazzle’. He designed Eunoia specifically to have that dazzle.

I think in the lower case of text types it should really be avoided and counteracted.

I put ’even color’ also in the title of this thread also, so here are my ruminations after reading about the ’edge effect’.

There are three different aspects of the relationship between black and white involved in a good roman text face.

1. Use or avoidance of the edge effect to enhance ’activate’ the whites possibly even having ’dazzle’, as discussed above.

2. A degree of regular rhythm or periodicity of the black verticals. This has been shown by Fourier transforms, and provides a regularity or grid against which the varying shapes of the letters are detected or ’read’ by the eye and brain.

3. Evenness of color. The density of the blacks in each letter, within the x-height particularly, is similar, and distributed in as balanced as way as the letter permits. This avoids distraction from the distinctive letter shape as the only different thing to be detected or read by the eye.

One more thought:

Could the edge effect or ’lateral interference’ be a reason why screen type is hard to read? Does low resolution and lit-from-behind type cause the neural network to be taxed?

This is an interesting summation. Thanks for doing the work to build it up!

1. I think that the ’edge effect’ is a hardwired optical illusion or that is of course part of the basic reality of whatever visual stimulus is being considered. In a way Notan is an acknowledgment that while we have ways of cutting up & interpreting and labeling things especially in terms of light & dark; there is ’a priori’ to any of that; a sensory reality which is a totality not a duality. So yes indeed; the edge effect can help to explain some phenomena within a person’s pre-analytic (Notanic) visual experience.

So I agree that the ’edge effect’ can be considered syththeticly with Notan. One way of synthesizing the two might be to say that while a machine, let’s say a scanner may detect the actual or measurable values of - let’s say of a page of text - it’s the human sensing of that page including many factors/illusions such as the ’edge effect’ but before conceptualization occurs that is the Notan of that page.

2. I think that while you can find rhythm or periodicity in some latin text forms, and the latin text may benefit from it to some minor degree I am having trouble making a meaningful connection of Notan or the ’edge effect’ to it. To my way of thinking the edge effect would of course be present it because edges are involved but that seems to be the end of it. Maybe I am missing something.

3. This avoids distraction from the distinctive letter shape as the only different thing to be detected or read by the eye. You put this well. Of course I prefer to think of Notanic balance because ’evenness’ sounds a little too mechanical, programatic or even literal (50/50) to me. Nonetheless I agree that whatever you call it - the goal should be to support rapid accurate recognition/processing of the forms by minimizing tonal distractions.

Would you expand on your ideas about the screen?

I have been hearing about how low rez sound taxes the brain to fill-in the missing music which leaves the brain less receptive to emotional content in the music. Do you have something like that in mind?

Eben, after reading about the edge effect, I am thinking that it is more useful to think of specific aspects of the black-white relationship in type, rather than talking about ’notan’ generally. For it seems that they are different variables as far as perception.

The stuff about ’activating the whites’ or ’designing the whites’ I am thinking is mainly about using the edge effect to make letters more vibrant, though Frutiger may have had more in mind.

Yes, I think a periodicity is quite a different variable from the edge effect. It does concern the distribution of black and white, though, especially through spacing. I think that it is a major, not minor matter in text. This is reinforced by an illustration in Unger’s book, where he has excessively tight, loose, and irregular spacing. The irregular spacing is strikingly the most disruptive to reading.

>I prefer to think of Notanic balance

As I said, I think using this one term is misleading because it puts these different phenomena—edge e