What Forms of Associative Learning Are Plants Capable of?

Chauncey Maher, Philosophy Department, Dickinson College, Carlisle

Recent work by Gagliano and her colleagues (Gagliano et al. 2016) indicates that plants learn by association. This is important. Some have drawn the conclusion that, together with other facts about plants, this shows that plants are cognitive systems (Gagliano et al 2017; Baluska et al. 2018; van Duijn 2018). Most others object that this inference is hasty (Allen 2017; Abramson and Calvo 2018). This leads to a debate about what cognition is, which sometimes bears fruit (Buckner 2015), but often is inconclusive (Allen 2017; van Duijn 2018). Here I pursue another fruitful line of response:  Are they capable of other forms of associative learning? These forms are well-known by psychologists, but haven’t yet been connected with plants. In this presentation, I make that connection, identifying several forms of associative learning that should be tested for in plants: latent inhibition, higher-order conditioning, sensory preconditioning, spontaneous recovery, US-devaluation, blocking, and trace conditioning. Testing for these abilities won’t settle whether plants are cognitive systems, but it will give us a more fine-grained understanding of how plants and animals are similar and different, which is at least as valuable as that. 

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