Ordinal Judgments and Summation of Nonvisible Sets of Food Items by Two Chimpanzees and a Rhesus Macaque.

Abstract

Two chimpanzees and a rhesus macaque rapidly learned the ordinal relations between 5 colors of containers (plastic eggs) when all containers of a given color contained a specific number of identical food items. All 3 animals also performed at high levels when comparing sets of containers with sets of visible food items. This indicates that the animals learned the approximate quantity of food items in containers of a given color. However, all animals failed in a summation task, in which a single container was compared with a set of 2 containers of a lesser individual quantity but a greater combined quantity. This difficulty was not overcome by sequential presentation of containers into opaque receptacles, but performance improved if the quantitative difference between sizes was very large.

Can nonhuman primates use tokens to represent and sum quantities?

“…Four of ten capuchins performed well in choosing the larger overall amount of food. Another four capuchins preferred the three-item token in all comparisons with single-item tokens, a result that we view as comparable to the failure of chimpanzees and a macaque in the Beran et al (2005) condition in which egg color cues were in conflict with total food amount. The remaining two capuchins in the Addessi et al (2007) experiment preferred the 3-item token only when presented in comparison to one single-item token (the training condition), whereas in all other conditions these two monkeys preferred the set that had the greater number of tokens.…”

“…Beran, Beran, Harris, and Washburn (2005) presented chimpanzees and a rhesus macaque (hereafter macaque) with a different variation of a quantity judgment task with symbols. These animals first chose between pairs of colored plastic eggs where each color egg always contained a specific and unique number of items (pink always contained five items, blue always contained four items, green always contained three items, orange always contained two items, and yellow always contained one item).…”

“…Beran et al (2005) used five different token values whereas Addessi et al (2007) used only two. Addessi et al (2007) presented more than two tokens of the lesser value in some of their conditions, whereas Beran et al (2005) did not (except in their final experiment where one of the chimpanzees improved albeit to only chance levels from below chance levels). Thus, a more direct comparative assessment is required to discern to what extent nonhuman animals can perform the symbol summation task.…”

A common representational system governed by Weber’s law: Nonverbal numerical similarity judgments in 6-year-olds and rhesus macaques

“…A particularly striking example of the developmental and evolutionary continuity found with respect to this analog magnitude representational system is the body of data showing that the accuracy and/or speed with which human adults, children, and nonhuman primates compare numerical magnitudes are modulated by ratio (Beran, 2001(Beran, , 2004Beran, Beran, Harris, & Washburn, 2005;Brannon & Terrace, 1998Dehaene, Dupoux, & Mehler, 1990;Judge, Evans, & Vyas, 2005;Moyer & Landauer, 1967;Nieder & Miller, 2004;Rumbaugh, Savage-Rumbaugh, & Hegel, 1987;Sekuler & Mierkiewicz, 1977;Smith, Piel, & Candland, 2003;Temple & Posner, 1998;Washburn & Rumbaugh, 1991). For example, even during the Wrst year of life, infants possess a ratio-dependent nonverbal system for representing number; by 6 months of age, infants discriminate large arrays with a 1:2 ratio but fail to discriminate sets with a 2:3 ratio (Lipton & Spelke, 2003;Xu & Spelke, 2000).…”

Addition and subtraction in wild New Zealand robins

“…Chimpanzees (Pan troglodytes) have been shown as capable of summing both small numbers (Boysen and Berntson, 1989) somewhat larger quantities (such as 3 + 4 + 1 or 2 + 2 + 3) (Beran, 2001, in a choice task), but failed to choose a combined greater quantity (comprised of two smaller quantities) over a single lesser quantity (Beran et al, 2005). In Flombaum et al's (2005) study, rhesus monkeys also successfully recognised addition of larger numbers (such as 4 + 4 = 8) when using lemons in that VoE study.…”