THE MORE THE BETTER. SPONTANEOUS CHOICE FOR LARGER NUMEROUSNESS IN THE DOMESTIC CAT.

We investigated domestic cats’ spontaneous ability to discriminate larger and smaller food quantities based on acoustic cues. Four 12-trials experiments were run with a total of 39 naïve subjects. Cats could hear different amounts of dry food pellets falling into two cans: approach, orientation towards and investigation of one of the latter were interpreted as choice for its content. Cats were always rewarded non-differentially. Relative position and order of presentation of large and small food amounts were counterbalanced. Discrimination thresholds were set at 4 vs 2 (Exp.1, N=24 cats) and 2 vs 1 pellets (Exp.2, N=17). Exp.3 and 4 were run on a subset of the sample in an effort to control for the intensity and duration of the continuous variable “sound”. The weight of the single pellet was equalised to that of the two pellets to catch up with the different intensity of the sound produced by 2 and 1 falling pellets (Exp.3, N=6). To compensate for its different duration the single pellet was made rebound, producing a second albeit attenuated sound (Exp.4, N=5). Results provide clear evidence of quantity discrimination and propensity for the largest amount: 80% (Exp.1) and 54% (Exp.2) of cats chose correctly significantly above chance level (≥10 correct choices on 12 trials). All 6 and 3 out of 5 cats (Exp.3 and 4) likewise largely satisfied the binomial criterion. The majority of all cats did so already in the first trial; the average choice made in the first 3 trials was predictive of subsequent performance.