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. 2009 Mar;91(2):257–286. doi: 10.1901/jeab.2009.91-257

Fig. 2.

Fig. 2

Photograph of intelligence panel and diagram (side view) of token receptacle used in Malagodi's research with rats as subjects and marbles as tokens. See text for details. From Malagodi (1967a). Reprinted with permission.