Behavioral task to assess physical causal understanding in rats (Rattus norvegicus)

Training of Motion Control May Not Improve Tool-Manipulation Ability in Rats (Rattus norvegicus)

“…Recent studies have investigated tool-use behavior in relatively low-visual-acuity rodents ( Prusky et al, 2002 ), including rats ( Rattus norvegicus ) ( Nagano and Aoyama, 2017a , b ; Nagano, 2019a , b , 2021 ) and degus ( Octodon degus ) ( Okanoya et al, 2008 ; Kumazawa-Manita et al, 2013 ) in controlled experimental settings. Previous studies on rats have reported that these rodents manipulated a rake-shaped tool based on the position of the food reward placed beyond their reach after undergoing tool-use training ( Nagano and Aoyama, 2017b ; Nagano, 2019b ).…”

“…However, the rats could manipulate the rake in the direction of the reward by using a strategy similar to that learned during training because they had the experience of obtaining the reward by using tools ( Nagano and Aoyama, 2017b ; Nagano, 2019b ). In contrast, Nagano (2021) , who used the same test implemented in the two previous studies ( Nagano and Aoyama, 2017b ; Nagano, 2019b ), reported that a rat manipulated the rake according to the reward position without prior experience of obtaining the reward with the tool or perceiving that a part of the tool came in contact with the reward that might cause it to move. However, only one out of the eight rats could manipulate the rake according to the position of the reward ( Nagano, 2021 ).…”

“…In contrast, Nagano (2021) , who used the same test implemented in the two previous studies ( Nagano and Aoyama, 2017b ; Nagano, 2019b ), reported that a rat manipulated the rake according to the reward position without prior experience of obtaining the reward with the tool or perceiving that a part of the tool came in contact with the reward that might cause it to move. However, only one out of the eight rats could manipulate the rake according to the position of the reward ( Nagano, 2021 ). Thus, it could not be concluded that rats have a primitive ability to manipulate tools according to food position.…”

“…Thus, it could not be concluded that rats have a primitive ability to manipulate tools according to food position. In the main training (rake-manipulation training) by Nagano (2021) , the rats were trained to move the rake laterally over successively greater distances without any food reward placed on the experimental apparatus. This training differed from the previous studies ( Nagano and Aoyama, 2017b ; Nagano, 2019b ), particularly in that it promoted the manipulation of the rake in the lateral direction.…”

“…The test mentioned above, where the rake was placed at the center and the food reward placed on either the left or right side of the rake, followed the food-obtaining training. Nagano (2021) suggested improving the methods for rake-manipulation and food-obtaining training as follows: the rake-manipulation training should employ stricter criteria to promote the rats’ monitoring of their own manipulation of the rake, and the rats should be offered the experience of pulling something (i.e., thread sewn into the food reward in the present study) to obtain the reward. This incorporates the suggestions of Connolly and Dalgleish (1989) and Ramsey et al (2021) that visual monitoring is necessary for tool-manipulation.…”