Impact of stimulus format and reward value on quantity discrimination in capuchin and squirrel monkeys

Abstract

Quantity discrimination abilities are seen in a diverse range of species with similarities in performance patterns, suggesting common underlying cognitive mechanisms. However, methodological factors that impact performance make it difficult to draw broad phylogenetic comparisons of numerical cognition across studies. For example, some Old World monkeys selected a higher quantity stimulus more frequently when choosing between inedible (pebbles) than edible (food) stimuli. In Experiment 1 we presented brown capuchin (Cebus [Sapajus] paella) and squirrel monkeys (Saimiri sciureus) with the same two-choice quantity discrimination task in three different stimulus conditions: edible, inedible, and edible replaced (in which choice stimuli were food items that stood in for the same quantity of food items that were given as a reward). Unlike Old World monkeys, capuchins selected the higher quantity stimulus more in the edible condition and squirrel monkeys showed generally poor performance across all stimulus types. Performance patterns suggested that differences in subjective reward value might motivate differences in choice behavior between and within species. In Experiment 2 we manipulated the subjective reinforcement value of the reward by varying reward type and delay to reinforcement and found that delay to reinforcement had no impact on choice behavior, while increasing the value of the reward significantly improved performance by both species. The results of this study indicate that species presented with identical tasks may respond differently to methodological factors such as stimulus and reward types, resulting in significant differences in choice behavior that may lead to spurious suggestions of species differences in cognitive abilities.

Gorillas (Gorilla gorilla gorilla) fail to learn abstract cues of differential outcomes in a novel cognitive bias test

“…This difference in responding could not be attributed solely to lack of inhibitory control when presented with edible items, because monkeys did not perform equally poorly when food items presented at choice were replaced with different food reward outcomes. A recent study extended this finding to two New World monkey species -brown capuchin and squirrel monkeys (Gazes, Billas & Schmitt, 2017). Capuchin monkeys selected the higher quantity more often when presented with edible items but squirrel monkeys performed poorly across all types of stimuli.…”

Surpassing the subitizing threshold: appetitive–aversive conditioning improves discrimination of numerosities in honeybees

“…There is some evidence that bees trained with appetitive differential conditioning may be able to discriminate ratios of 0.57 (4 versus 7) above the threshold of 4 objects; however, this is still an open question as these bees failed at discriminating the less challenging ratio of 0.50 (4 versus 8). Honeybees are currently at a level of quantity discrimination observed in species such as African grey parrots (Al Aïn et al, 2009), capuchin monkeys (Addessi et al, 2008;Gazes et al, 2018), squirrel monkeys (Gazes et al, 2018), dolphins (Jaakkola et al, 2005), ponies (Gabor and Gerken, 2018), jungle crows (Bogale et al, 2011) and guppies (Bisazza et al, 2014). The question of whether the introduction of an aversive outcome for an incorrect choice improves performance has been asked for colour discrimination tasks in bees (Avargues-Weber et al, 2010;Chittka et al, 2003), but this is the first time appetitive and appetitive-aversive differential conditioning have been directly compared for a numerical visual task.…”

“…Quantity discrimination has been explored in a number of species through different methods (e.g. spontaneous choice versus training; limited versus extensive training), which sometimes yield different results (Agrillo and Bisazza, 2014;DeWind and Brannon, 2012;Gatto et al, 2017;Gazes et al, 2018;Miletto Petrazzini et al, 2018). The ability to discriminate between quantities varies across different species, with insects such as mealworm beetles able to discriminate ratios (calculated by dividing the lower number by the higher number, such as 1 versus 4 and 1 versus 3) of 0.25-0.33 (Carazo et al, 2009).…”

“…The ability to discriminate between quantities varies across different species, with insects such as mealworm beetles able to discriminate ratios (calculated by dividing the lower number by the higher number, such as 1 versus 4 and 1 versus 3) of 0.25-0.33 (Carazo et al, 2009). Species that can discriminate the more difficult ratio of 0.80 include monkeys (Addessi et al, 2008;Gazes et al, 2018), jungle crows (Bogale et al, 2011), Shetland ponies (Gabor and Gerken, 2018), Clark's nutcrackers (Tornick et al, 2015) and dolphins (Jaakkola et al, 2005). Some animals including elephants (Irie-Sugimoto et al, 2009), great apes (Hanus and Call, 2007), Mexican jays (Kelly, 2016), western scrub jays (Kelly, 2016) and guppies (Bisazza et al, 2014; can discriminate ratios over 0.80.…”

More evidence that less is better: Sub-optimal choice in dogs

“…Failure to behave optimally does not reflect an inability to discriminate between quantities. Non-human animals including great apes (Beran, 2001;Call, 2000;Hanus & Call, 2007;Rumbaugh, Savage-Rumbaugh, & Hegel, 1987), old world monkeys (Jordan & Brannon, 2006), new world monkeys (e.g., Addessi, Crescimbene, & Visalberghi, 2008;Anderson, Awazu, & Fujita, 2000;Gazes, Billas, & Schmitt, 2017), rodents (Panteleeva, Reznikova, & Vygonyailova, 2013), birds (Kelly, 2016), fish (Agrillo, Dadda, & Bisazza, 2007;Agrillo, Dadda, Serena, & Bisazza, 2008), amphibians (Uller, Jaeger, Guidry, & Martin, 2003), and canids (Baker, Shivik, & Jordan, 2011;Utrata, Virányi, & Range 2012), including domestic dogs (Baker, Morath, Rodzon, & Jordan, 2012;Miletto Petrazzini & Wynne, 2016;Prato-Previde, Marshall-Pescini, & Valsecchi, 2008;Ward & Smuts, 2007), have all been found to be capable of quantity discrimination and, where tested, show a preference for larger quantities over smaller quantities of the same food. We also found evidence for such a preference.…”