In brief: The legibility of digits in a crossed out or highlighted series appears to block quick location of the next digit in the series to cross out.
Description: Today I was helping a friend do a manual tally of her teaching evaluations. To do this I set up a Word document with a table. In the table there was a row for each question we were to tally, with blank boxes in the row for each score on the rating scale (Excellent, Very good, etc.--lots of excellents in fact!). The plan was to record, in each box, the number of evaluations with a given score, as she read the scores aloud. Specifically, the plan was to use the tallying strategy where you make a vertical stroke for each item, up to four strokes, and then make a horizontal stroke through the group, to count five. I thought this would make for easier totalling at the end.
But it turns out that when you're doing multiple counts in different boxes, and looking from box to box, it's hard to quickly see whether there are four strokes in the group, i.e., whether a horizontal stroke is called for. (It's very different if you're doing just one count, in which case the four vertical strokes, then one horizontal, system works well.)
So, I came up with another idea. In each box, I typed the following:
0 : 1 2 3 4 5 6 7 8 9
1 : 0 1 2 3 4 5 6 7 8 9
2 : 0 1 2 3 4 5 6 7 8 9
3 : 0 1 2 3 4 5 6 7 8 9
4 : 0 1 2 3 4 5 6 7 8 9
5 : 0 1 2 3 4 5 6 7 8 9
That way, all I had to do was cross off the digits in sequence, and at the end of the tally, I could read off the count. (E.g., if the digits up until 3 in the third row were crossed off, the count was 23.)
But still there was a perceptual problem. I was doing multiple counts, in a table with six rows and six columns. And to fit the numbers in, they were very small and crowded together. Searching for the right box, and then quickly, without thinking, seeing and locating the next number to be crossed off was still difficult. Crossing out ticked off numbers with a diagonal stroke in blue ink didn't work very well in making the location of the next number stand out. Too hard to see the numbers stroked out. So, I tried a highlighter. Much better. As you spotted, bingo-like, the numbers, a sort of bar extended across the counted numbers. But, it was still strangely hard to see instantly where the next number to be marked off was. More, the highlighters was a bit splotchy. So, I tried diagonal strokes with a red pen, and then scratch outs with a red pen.
Then, by luck, I tried the thing that worked, and had a pragmatic and conceptual epiphany. Making a sort of gamma shaped loop in blue ink through a digit (like a fish with its head pointing down and its tail up the page) made the task very easy.
Observation: I think the key here is that the gamma shaped loop made the digit unreadable. I think this is because the loop crossed the digit's figure in enough--and the right--places to make that figure illegible as a digit. Like camouflage making an animal body be hard to see, it broke up the boundaries of the figure.
So the digit no longer appeared as: crossed-out digit; or: differently-coloured-digit; but: as not a digit at all.
What's interesting here is that the highlighted digits had a different gestalt than the unreadable digits: the former were: a row of digits with a bar of coloured dots over top; the latter, a series of other figures, followed by a digit. And in the former case it was harder to search for the next digit to mark.
Now this is a bit odd, because the bar of coloured dots is pretty clearly visible, and its pretty clearly visible where it stops, and yet it was hard to land with precision on the next number, and to see the numbers that had been dotted as counted off or used up.
I would suggest this is because in a sequence of digits (say 1 2 3 4 5) with pink highlighter over them, two things were visually overlaid: 1) A series of legible digits, which extended into the next digits, 6 and 7, and so did not mark off the 6 as different than the 5, and thence as: the next digit to be marked off. 2) That series of digits as grouped by colour into a gestalt. But, there is a sort of rivalry between these two things: the legible digits still call to be read as digits, over and above the visual expanse they occupy, or the tinting of that expanse, or that expanse as a gestalt.
So, methinks I should search for literature on rivalry and distinctions between visual and digit/letter perceptual channels.
Also: I wonder if people with number-colour synaesthesia might have a different experience of the problem I've outlined above. Also: I wonder if part of learning to read is learning to have this sort of rivalry, i.e. if you can't read digits as such, then the digits won't compete with highlighting. But then we could also test for things that would compete. I'd bet that for infants, little happy faces would compete.
Also, this reminds me of a dissocation in which subjects who experience themselves as inverted on entry into microgravity experience an instrument dial as inverted, but the numbers on it as non-inverted.
This suggests something like: seeing digits is different than seeing the position they occupy, since seeing the highlighted but legible digit grabs your attention.