Conditioning and Associative Learning

Associative learning is the process whereby humans and other animals learn the predictive relationship between cues in their environment. This process underlies simple forms of learning from rewards, such as classical and operant conditioning. In this chapter, we introduce the basics of associative learning and discuss the role that memory processes play in the establishment and maintenance of this learning. We then discuss the role that associative learning plays in human memory, including through paired associate learning, the enhancement of memory by reward, and the formation of episodic memories. Finally, we illustrate how the memory process influences choice in decision-making, where associative learning allows people to learn the values of different options. We conclude with some suggestions about how models of associative learning, memory, and choice can be integrated into a single theoretical framework.

Asymmetric Weights and Retrieval Practice in an Autoassociative Neural Network Model of Paired-Associate Learning

Rizzuto and Kahana (2001) applied an autoassociative Hopfield network to a paired-associate word learning experiment in which (1) participants studied word pairs (e.g., ABSENCE-HOLLOW), (2) were tested in one direction (ABSENCE-?) on a first test, and (3) were tested in the same direction again or in the reverse direction (?-HOLLOW) on a second test. The model contained a correlation parameter to capture the dependence between forward versus backward learning between the two words of a word pair, revealing correlation values close to 1.0 for all participants, consistent with neural network models that use the same weight for communication in both directions between nodes. We addressed several limitations of the model simulations and proposed two new models incorporating retrieval practice learning (e.g., the effect of the first test on the second) that fit the accuracy data more effectively, revealing substantially lower correlation values (average of .45 across participants, with zero correlation for some participants). In addition, we analyzed recall latencies, finding that second test recall was faster in the same direction after a correct first test. Only a model with stochastic retrieval practice learning predicted this effect. In conclusion, recall accuracy and recall latency suggest asymmetric learning, particularly in light of retrieval practice effects.

Memory recall involves a transient break in excitatory-inhibitory balance

The brain has a remarkable capacity to acquire and store memories that can later be selectively recalled. These processes are supported by the hippocampus which is thought to index memory recall by reinstating information stored across distributed neocortical circuits. However, the mechanism that supports this interaction remains unclear. Here, in humans, we show that recall of a visual cue from a paired associate is accompanied by a transient increase in the ratio between glutamate and GABA in visual cortex. Moreover, these excitatory-inhibitory fluctuations are predicted by activity in the hippocampus. These data suggest the hippocampus gates memory recall by indexing information stored across neocortical circuits using a disinhibitory mechanism.

Anterior thalamic nuclei: A critical substrate for non-spatial paired-associate memory

The anterior thalamic nuclei (ATN), a central node in a complex memory system, process spatial and temporal memory. Here, we show that ATN lesions do not affect acquisition of a simple odour discrimination or a simple object discrimination in a runway apparatus. The same procedures were used to test learning of an arbitrary association between non-spatial object-odour pairings (A+X or B+Y were rewarded; but not A+Y or B+X). If ATN lesions recapitulate hippocampal function, specifically CA1 function, then they should disrupt acquisition only when an explicit delay (i.e., a 10-second trace) is inserted between the odour and object. Acquisition was completely abolished by ATN lesions, irrespective of the presence of the temporal trace, and despite extensive training (50x12-trial sessions). Faster acquisition with the 10-second trace was found in the sham-lesion rats. During recall, 5 days after criterion, sham rats but not ATN-lesion rats showed elevated Zif268 expression in hippocampal CA1 for the trace compared to no-trace condition; both sham and lesion rats tested in the trace condition showed increased IEG expression in the superficial layers of the prefrontal cortex and retrosplenial cortex. ATN lesions markedly reduced Zif268 expression in the prefrontal cortex and retrosplenial cortex. This is the first evidence that ATN lesions impair non-spatial paired-associate tasks. The findings suggest that the ATN influence memory beyond time and space, and constitute a critical neural structure for learning arbitrary associations even in the task version that is not disrupted by hippocampal lesions.

EFFECTS OF LEARNING DIRECTION IN RETRIEVAL PRACTICE ON EFL VOCABULARY LEARNING

In paired-associate learning, there are two learning directions: L2 to L1 (L2 words as stimuli and L1 words as responses) and L1 to L2 (L1 words as stimuli and L2 words as responses). Results of previous studies that compared the effects of the two learning directions are not consistent. We speculated that the cause of this inconsistency may be L2 proficiency, as the strengths of the lexical links between L2 and L1 are different depending on the learner’s L2 proficiency. This hypothesis was examined with 28 native speakers of Japanese learning English. Participants studied novel English words in the two learning directions. The results of posttests showed that for lower-proficiency learners, L2-to-L1 learning was more effective than L1-to-L2 learning, while for higher-proficiency learners, L1-to-L2 learning was more effective. The findings suggest that L2 proficiency influences the effects of learning direction on vocabulary learning.

Semantic relatedness retroactively boosts memory and promotes memory interdependence across episodes

Two fundamental issues in memory research concern when later experiences strengthen or weaken initial memories and when the two memories become linked or remain independent. A promising candidate for explaining these issues is semantic relatedness. Here, across five paired associate learning experiments (N=1000), we systematically varied the semantic relatedness between initial and later cues, initial and later targets, or both. We found that learning retroactively benefited long-term memory performance for semantically related words (versus unshown control words), and these benefits increased as a function of relatedness. Critically, memory dependence between initial and later pairs also increased with relatedness, suggesting that pre-existing semantic relationships interdependence for memories formed across episodes. We also found that modest retroactive benefits, but not interdependencies, emerged when subjects learned via studying rather than practice testing. These findings demonstrate that semantic relatedness during new learning retroactively strengthens old associations while scaffolding new ones into well-fortified memory traces.

Psychopathic features, paired-associate learning, and lexical decision-making in children

This thesis explored potential links between psychopathic features and difficulties with abstract semantic processing in a clinical convenience sample of children aged 6 through 11. Correlational analyses investigated relationships between parent-reported Antisocial Process Screening Device (APSD) and Inventory of Callous-Unemotional (ICU) scores, and differences in children's concrete versus abstract performance on paired-associate (PA) and lexical decision (LD) tasks. The expected positive correlations with callous-unemotional traits were not found. However, parent-reported APSD impulsivity, APSD total, and ICU total scores were negatively correlated with differences in LD accuracy. The analyses failed to reveal anticipated differences between concrete and abstract task performance. While the null findings suggest numerous issues with the study protocol, several solutions are proposed, and the importance of measuring the sub-factors of psychopathy (impulsivity, narcissism, CU traits) in future investigations of child cognitive functioning was emphasized.

Psychopathic features, paired-associate learning, and lexical decision-making in children

This thesis explored potential links between psychopathic features and difficulties with abstract semantic processing in a clinical convenience sample of children aged 6 through 11. Correlational analyses investigated relationships between parent-reported Antisocial Process Screening Device (APSD) and Inventory of Callous-Unemotional (ICU) scores, and differences in children's concrete versus abstract performance on paired-associate (PA) and lexical decision (LD) tasks. The expected positive correlations with callous-unemotional traits were not found. However, parent-reported APSD impulsivity, APSD total, and ICU total scores were negatively correlated with differences in LD accuracy. The analyses failed to reveal anticipated differences between concrete and abstract task performance. While the null findings suggest numerous issues with the study protocol, several solutions are proposed, and the importance of measuring the sub-factors of psychopathy (impulsivity, narcissism, CU traits) in future investigations of child cognitive functioning was emphasized.