I had difficulty with that trial, and I'd forget on the 3 icon one. 😕 took me around 40 or so tries to get it done.
I got through by saying the icons out loud as I walked by the arc. You'll need to use small syllable words too, because if the words are too long (Like "Flower Pot" or "Lawn Mower") you won't have enough time to say them all.
I used Pot, Can (Watering can), Boot, Spade (Shovel), Bird, Fence, Mower and Barrow. I wish I could help better than that, but saying them out loud, though it felt and sounded silly, really helped. Especially since it was easier to recall what I had just said. It still took quite a few tries with this method, but it worked.
I'm sorry I can't help more, that's all I got.