Associations between Attention and Implicit Associative Learning in Healthy Adults: The Role of Cortisol and Salivary Alpha-Amylase Responses to an Acute Stressor.

Linda Becker,Nicolas Rohleder

doi:10.3390/brainsci10080544

Abstract

In this study, we investigated the associations between implicit associative learning with the cortisol and salivary alpha-amylase (sAA) stress response to an acute stressor as well as their associations with attention. Eighty one healthy adults (25 male) participated and either performed the socially evaluated cold-pressor test (SECPT) or a warm-water control task (WWT). Either prior to or immediately after the SECPT/WWT, participants implicitly learned digit-symbol pairs. A not-previously announced recall test was conducted about 20 min after the SECPT/WWT. Attention was assessed by means of a Stroop task at nine time points over the course of the experiment. Memory recall performance was not significantly associated with the acquisition time point (pre or post stressor) and did not significantly differ between the responder groups (i.e., non-responders, sAA-and-cortisol responders, only sAA responders, and only cortisol responders). Attentional performance increased throughout the experiment (i.e., reaction times in the Stroop task decreased). No differences in the attentional time course were found between the responder groups. However, some associations were found (puncorrected < 0.05) that did not pass the multiple comparison adjusted alpha level of αadjusted = 0.002, indicating different associations between attention and implicit learning between the responder groups. We conclude that the associations of sAA and cortisol responses with implicit learning are complex and are related to each other. Further studies in which both (sAA and cortisol responses) are selectively (de-) activated are needed. Furthermore, different learning tasks and less—potentially stressful—attentional assessments should be used in future research. Moreover, field studies are needed in which the associations between acute stress and implicit associative learning are investigated in everyday life.

Highlights

One of the most important cognitive functions for a successful and happy life is memory
We conclude that the associations of salivary alpha-amylase (sAA) and cortisol responses with implicit learning are complex and are related to each other
We found that performance during the acquisition phase was not significantly associated with attentional performance, i.e., it was not correlated with reaction times or error rates in the Stroop task at any of the time points

Summary

Introduction

One of the most important cognitive functions for a successful and happy life is memory. Memory is much more than remembering the names of loved ones or telephone numbers. It can be the result of learning new skills or associations, which mostly happens unconsciously. This unconsciously learned information is called implicit memory, the opposite of explicit memory [1]. Another distinction that has often been made, is whether the hippocampus is involved in the learning process or not, which leads to so-called hippocampus-dependent or non-hippocampus-dependent memory [2]. Hippocampus-dependent memory includes both explicit memory as well as some forms of implicit memory (e.g., associative memory; [3,4,5])

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