I think you would be interested in the topic of subitizing https://en.wikipedia.org/wiki/Subitizing https://en.wikipedia.org/wiki/Subitizing > The accuracy, sp

I think you would be interested in the topic of subitizing https://en.wikipedia.org/wiki/Subitizing https://en.wikipedia.org/wiki/Subitizing > The accuracy, speed, and confidence with which observers make judgments of the number of items are critically dependent on the number of elements to be enumerated. Judgments made for displays composed of around one to four items are rapid,[2] accurate[3] and confident.[4] However, as the number of items to be enumerated increases beyond this amount, judgments are made with decreasing accuracy and confidence.[1] In addition, response times rise in a dramatic fashion, with an extra 250–350 ms added for each additional item within the display beyond about four.[5] I can't spot the references I thought I'd see here but I recall there being work around training this and seeing people improve up to around 7-8.