The spider monkeys were able to master all cognitive tasks that were presented to them: they successfully located the food items which they observed being hidden under one of two colored cups, thus demonstrating their ability of object permanence; they successfully located the food items hidden – out of their sight – under one of two colored cups, thus demonstrating their ability to learn by association via relating their assigned cup color to the food reward; they successfully selected the larger of two quantities of food, thus demonstrating their ability to discriminate relative quantities; they successfully selected the cards bearing the higher number of dots, both with equally- and various-sized dots, thus demonstrating their ability to discriminate discrete numbers, independent of dot size and pattern; and they successfully located the food items hidden under their assigned colored cup after a 4-month break, thus demonstrating their ability to memorize visual information on a long term.

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