In humans, a distinction can be made between implicit or procedural learning (involving stimulus-response associations) and explicit or declarative learning (involving verbalizable rules) that is relatively easy to make in verbal humans. According to several investigators, it is also possible to make such a distinction in nonverbal animals. One way is by training them on a conditional discrimination task (e.g., matching-to-sample) in which reinforcement for correct choice on the current trial is delayed until after a choice is made on the next trial – a method known as the 1-back procedure. According to Smith, Jackson, and Church ( Journal of Comparative Psychology, 134(4), 423–434, 2020), the delay between the sample-correct-comparison response on one trial and reinforcement obtained on the next trial is too long for implicit (associative) learning. Thus, according to this theory, learning must be explicit. In the present experiments we trained pigeons using the 1-back procedure. In Experiment 1, pigeons were trained on red/green 1-back matching using a non-correction procedure. Some of the pigeons showed significant learning. When a correction procedure was introduced, all the pigeons showed evidence of learning. In Experiment 2, new pigeons learned red/green 1-back matching with the correction procedure. In Experiment 3, new pigeons learned symbolic 1-back matching with yellow and blue conditional stimuli and red/green choice stimuli. Thus, pigeons can learn using 1-back reinforcement. Although it would appear that the pigeons acquired this task explicitly, we believe that this procedure does not adequately distinguish between implicit and explicit learning.
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Arbuthnott, G. W., Ingham, C. A., & Wickens, J. R. (2000). Dopamine and synaptic plasticity in the neostriatum. Journal of Anatomy, 196, 587–596
Ashby, F. G., & Ennis, J. M. (2006). The role of the basal ganglia in category learning. In: B. H. Ross (Ed.), The psychology of learning and motivation (Vol. 46, pp. 1–36). Academic Press
Ashby, F. G., & Maddox, W. T. (2011). Human category learning 2.0. Annals of the New York Academy of Sciences, 1224, 147–161
Ashby, F. G., & Valentin, V. V. (2017). Multiple systems of perceptual category learning: Theory and cognitive tests. In H. Cohen & C. Lefebvre (Eds.), Handbook of categorization in cognitive science (pp. 157–188). Academic Press
Barnes, T. D., Kubota, Y., Hu, D., Jin, D. Z., & Graybiel, A. M. (2005). Activity of striatal neurons reflects dynamic encoding and recoding of procedural memories. Nature, 437, 1158 –1161
Calabresi, P., Pisani, A., Centonze, D., & Bernardi, G. (1996). Role of Ca2 in striatal LTD and LTP. Seminars in the Neurosciences, 8, 321–328
Capaldi, E. J. (1971). Memory and learning: a sequential viewpoint. In: W. K. Honig and H. James (Eds.), Animal Memory. Academic
Castro, L., & Wasserman, E. A. (2013). Information-seeking behavior: exploring metacognitive control in pigeons. Animal Cognition, 16, 241–254
Couchman, J. J., Coutinho, M. V. C., Beran, M. J., & Smith, J. D. (2010). Beyond stimulus cues and reinforcement signals: A new approach to animal metacognition. Journal of Comparative Psychology, 124, 356–368
Crystal, J. D., & Foote, A. L. (2009). Metacognition in animals. Comparative Cognition & Behavior Reviews, 4, 1-16
Foote, A. L., & Crystal, J. D. (2007). Metacognition in the rat. Current Biology, 17, 551-555
Grant, D. S. (1976). Effect of sample presentation time on long-delay matching in the pigeon. Learning and Motivation, 7, 580-590
Hampton, R. R. (2001). Rhesus monkeys know when they remember. Proceedings of the National Academy of Sciences of the United States of America, 98, 5359–5362
Hull, C. L. (1943). Principles of behavior. Appleton-Century-Crofts
Jozefowiez, J., Staddon, J. E. R., & Cerutti, D. T. (2009). Metacognition in animals: how do we know that they know? Comparative Cognition & Behavior Reviews, 4, 29-39
Kirchner, W. K. (1958). Age differences in short-term retention of rapidly changing information. Journal of Experimental Psychology, 55, 352-358
Le Pelley, M. E. (2012). Metacognitive monkeys or associative animals? Simple reinforcement learning explains uncertainty in nonhuman animals. Journal of Experimental Psychology: Learning, Memory, and Cognition, 38, 686-708
Le Pelley, M. E., Newell, B. R., & Nosofsky, R. M. (2019). Deferred feedback does not dissociate implicit and explicit category learning systems: Commentary on Smith et al. (2014). Psychological Science, 30, 1403-1409
Maddox, W. T., Ashby, F. G., & Bohil, C. J. (2003). Delayed feedback effects on rule-based and information-integration category learning. Journal of Experimental Psychology: Learning, Memory, and Cognition, 29, 650–662
Mishkin, M., Malamut, B., & Bachevalier, J. (1984). Memories and habits: Two neural systems. In G. Lynch, J. L. McGaugh, & N. M. Weinberger (Eds.), Neurobiology of human learning and memory (pp. 65–88). Guilford Press
Misulis, K. E., & Fakhoury, T. (2001). Spehlmann's Evoked Potential Primer. Butterworth-Heinemann
Panoz-Brown, D. Lyer, V., Carey, L. M., Sluka, C. M., Rajic, G., Kestenman, J., Gentry, M., Brotherridge, S., Somekh, I., Corbin, H. E., Tucker, K. G., Almeida, B., Hex, S. B., Garcia, K. D., Hohmann, A. G., & Crystal, J. D. (2018). Replay of episodic memories in the rat. Current Biology, 28, 1628-1634
Riley, A. L., & Baril, L. (1976). Conditioned taste aversions: A bibliography. Animal Learning & Behavior, 4, 1S-13S
Roberts, W. A., McMillan, N., Musolino, E., & Cole, M. (2012). Information seeking in animals: Metacognition? Comparative Cognition & Behavior Reviews, 7, 85-109
Smith, J. D., Beran, M. J., Redford, J. S., & Washburn, D. A. (2006). Dissociating uncertainty responses and reinforcement signals in the comparative study of uncertainty monitoring. Journal of Experimental Psychology: General, 135, 282–297
Smith, J. D., Ashby, F. G., Berg, M. E., Murphy, M. S., Spiering, B., Cook, R. G., & Grace, R. C. (2011). Pigeons’ categorization may be exclusively nonanalytic. Psychonomic Bulletin & Review, 18, 414–421
Smith, J. D., Beran, M. J., Couchman, J. J., & Coutinho, M. V. C. (2008). The comparative study of metacognition: Sharper paradigms, safer inferences. Psychonomic Bulletin & Review, 15, 679-691
Smith, J. D., Boomer, J., Zakrzewski, A. C., Roeder, J. L., Church, B. A., & Ashby, F. G. (2014). Deferred feedback sharply dissociates implicit and explicit category learning. Psychological Science, 25, 447–457. https://doi.org/10.1177/0956797613509112.
Smith, J. D., & Church, B. A. (2018). Dissociable learning processes in comparative psychology. Psychonomic Bulletin and Review, 25, 1565–1584. https://doi.org/10.3758/s13423-017-1353-1.
Smith, J. D., Jackson, B. N., & Church, B. A. (2020). Monkeys (Macaca mulatta) learn two-choice discriminations under displaced reinforcement. Journal of Comparative Psychology, 134(4), 423–434. https://doi.org/10.1037/com0000227.
Smith, J. D., Jamani, S., Boomer, J. & Church, B. A. (2018). One-back reinforcement dissociates implicit-procedural and explicit-declarative category learning. Memory and Cognition, 46, 261-273
Smith, J. D., Schull, J., Strote, J., McGee, K., Egnor, R., & Erb, L. (1995). The uncertain response in the bottlenosed dolphin (Tursiops truncatus). Journal of Experimental Psychology: General, 124, 391–408
Smith, J. D., Shields, W. E., Schull, J., & Washburn, D. A. (1997). The uncertain response in humans and animals. Cognition, 62, 75–97
Stagner, J. P., & Zentall, T. R. (2010). Suboptimal choice behavior by pigeons. Psychonomic Bulletin & Review, 17, 412-416
Wills, A. J. et al., (2019). Dissociable learning processes, associative theory, and testimonial reviews: A comment on Smith and Church (2018). Psychonomic Bulletin & Review, 26, 1988-1993
Woodruff-Pak, D. S., & Disterhoft, J. F. (2007). Where is the trace in trace conditioning? Trends in Neurosciences, 31, 105-112
Yagishita, S. et al. (2014). A critical time window for dopamine actions on the structural plasticity of dendritic spines. Science, 345, 1616–1620
Zentall, T. R., Andrews, D. M., & Case, J. P. (2018). Sameness may be a natural concept that does not require learning. Psychological Science, 29, 1185-1189
Zentall, T. R., Edwards, C. A., Moore, B. S., & Hogan, D. E. (1981). Identity: The basis for both matching and oddity learning in pigeons. Journal of Experimental Psychology: Animal Behavior Processes, 7, 70-86
Zentall, T. R., & Hogan, D. E. (1974). Abstract concept learning in the pigeon. Journal of Experimental Psychology, 102, 393-398
Zentall, T. R., & Hogan, D. E. (1975). Concept learning in the pigeon: Transfer of matching and nonmatching to new stimuli. American Journal of Psychology, 88, 233-244
Zentall, T. R., & Hogan, D. E. (1976). Pigeons can learn identity, difference, or both. Science, 191, 408-409
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Nosarzewska, A., Peng, D.N. & Zentall, T.R. Pigeons acquire the 1-back task: Implications for implicit versus explicit learning?. Learn Behav (2021). https://doi.org/10.3758/s13420-021-00468-3
- Explicit learning
- Implicit learning
- 1-back procedure