The bounding box of a sign appears to be an effective feature. According to these results, 25 to 35 per cent accuracy can be obtained solely by considering the bounding box.
This is a little surprising, to say the least. This essentially says that by looking only at two points in space we can identify the signs in about three out of every ten cases.
At this point, no particular pattern is obvious about the relative quality of various learners, except that IBL2 and IBL3 do not appear to be doing very well. Also, the results for adam are quite good, but they should be taken carefully, since this is the data-set for which no fatigue adjustment technique was employed.