Quantity Discrimination in Wolves (Canis lupus) - PubMed (original) (raw)

Quantity Discrimination in Wolves (Canis lupus)

Ewelina Utrata et al. Front Psychol. 2012.

Abstract

Quantity discrimination has been studied extensively in different non-human animal species. In the current study, we tested 11 hand-raised wolves (Canis lupus) in a two-way choice task. We placed a number of food items (one to four) sequentially into two opaque cans and asked the wolves to choose the larger amount. Moreover, we conducted two additional control conditions to rule out non-numerical properties of the presentation that the animals might have used to make the correct choice. Our results showed that wolves are able to make quantitative judgments at the group, but also at the individual level even when alternative strategies such as paying attention to the surface area or time and total amount are ruled out. In contrast to previous canine studies on dogs (Canis familiaris) and coyotes (Canis latrans), our wolves' performance did not improve with decreasing ratio, referred to as Weber's law. However, further studies using larger quantities than we used in the current set-up are still needed to determine whether and when wolves' quantity discrimination conforms to Weber's law.

Keywords: Weber’s law; domestication; numerical competence; wolf.

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Figures

Figure 1

Figure 1

The experimental set-up of the apparatus from the wolf’s perspective. The draft shows the table, the buzzer and the opaque cans with the rewarding tubes, which are leading from the air lock into the testing enclosure.

Figure 2

Figure 2

Illustration of the task 4 vs. 1 in Time control.

Figure 3

Figure 3

Illustration of the task 4 vs. 1 in Stone control.

Figure 4

Figure 4

Performance of the wolves across all conditions (■ = quantity test, ▲ = time control, △ = stone control) shown as proportion of correct choices for the given ratios. The ratio 0.33 and 0.75 were only present in the quantity test.

Figure 5

Figure 5

Performance of the wolves given as the proportion of correct choices for every session across the different experimental conditions (Quantity test: 1–8, Time control: 1–4, Stone control: 1–4).

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