Target decision or action? The role of action in the attentional boost effect

Abstract

The attentional boost effect (ABE) represents a phenomenon in which, in some dual tasks, increasing attention to a brief target in a detection task can enhance memory for unrelated items that are presented at the same time (relative to distractor-paired items). The ABE was different from the dual-task interference phenomenon found in previous studies, and to explain the ABE, Swallow and Jiang proposed a dual-task interaction model. This model claimed that the ABE was mainly triggered by the decision that an item is a target, which can lead to the transient but widespread perceptual enhancement of information by inducing a temporal selection mechanism. However, in ABE studies, the target detection tasks always coincide with Go responses that require action. One recent study found that action can enhance memory for unrelated items, which was called action-induced memory enhancement (AIME). Therefore, it is unclear whether the ABE is induced by the action or the target decision. To address this question, in the present study, the verbal paradigm of the ABE was modified and designed with a NoGo-target detection condition (NoGo-targets vs. Go-distractors) to separate target items from action responses, and a traditional Go-target detection condition (Go-targets vs. NoGo-distractors) was used for comparison. If the ABE is mainly triggered by the target decision, then NoGo-target detection could trigger the cross-conditional ABE (relative to NoGo-distractor items). In contrast, if the ABE is mainly triggered by the action, the NoGo-target items will not have any memory advantage. The present study included four experiments, and 137 valid data points were collected, including 33 valid data points in Experiment 1, 35 valid data points in Experiment 2, 36 valid data points in Experiment 3, and 33 valid data points in Experiment 4. The only difference among the four experiments was that the ratio of target-to-distractor items was different during the dual-task encoding phase. In Experiment 1, the ratio of target-to-distractor items was the same as that in the classic ABE verbal paradigm (1:5) to explore the role of AIME in the ABE. In Experiments 2 and 3, the ratio of target-to-distractor items was set to 1:1 and 1:2 to explore the role of the AIME and target decision in the ABE with different action frequencies. In Experiment 4, blank words (words without detection stimuli) were added in the detection phase to separate the action frequency (2/3) from the target frequency (relative to distractors; Go-targets: 4/5; NoGo-targets: 1/5) and verify the dynamic trade-off model of the target decision and action reaction proposed in the present study. Each experiment contained two conditions, namely, NoGo-target detection and Go-target detection, and each condition consisted of two phases, namely, a dual-task encoding phase and a recognition phase. During the dual-task encoding phase, a series of memory stimuli (words) and detection stimuli (coloured circles presented, 1 cm below the words) were presented at the same time, and the participants were asked to simultaneously perform the memory and detection tasks. During the recognition phase, only memory stimuli were presented, and the participants were required to judge the stimuli as old or new. The only difference between the NoGo-target condition and Go-target condition was reflected in the instructions for the detection task: in the Go-target condition, the participants were asked to press the space bar as quickly as possible when they saw the target circles (e.g., a red circle with Go-response) but did not need to respond when they saw other-coloured circles (i.e., distractor circles with NoGo-responses); in contrast, in the NoGo-target condition, the participants were required to press the space bar as quickly as possible for all circles (i.e., distractor circles with Go-responses) but withhold a button press for the target circle (e.g., a red circle with NoGo-response). The results showed that NoGo-target detection enhanced memory performance for target items (relative to Go-distractor/NoGo-distractor items) in the four experiments. First, it was found that the NoGo-target items were better remembered than the Go-distractor items and NoGo-distractor items in Experiment 1 (1:5 ratio), and performance with the Go-distractor items was worse than that with the NoGo-distractor items, showing that the ABE was triggered by the target decision without an action response and that actions had inhibitory effects at high frequencies. Second, it was found that the NoGo-target items were better recognized than the NoGo-distractor items but not better than the Go-distractor items in Experiment 2 (1:1 ratio), and the AIME was found with the Go-distractor items, showing that the boosting effect from the target decision on background information is robust, but the AIME affected the generation of the ABE within the NoGo-target condition. Third, it was found that NoGo-target items were better remembered than Go-distractor items and NoGo-distractor items in Experiment 3 (1:2 ratio), and there was no difference in memory performance between the Go-distractor items and the NoGo-distractor items, indicating that action frequency affected the generation of the ABE by adjusting the AIME. Finally, it was found that at 2/3 of the action frequency, both the Go-target detection with high target frequency and the NoGo-target detection with low target frequency triggered the ABE, and the memory performance was similar between the Go-distractor items and the NoGo-distractor items, indicating again that action frequency affected the generation of the ABE by adjusting the AIME, verifying the hypothesis of the dynamic trade-off model. Overall, the results of all four experiments found memory advantages with the NoGo-target items, but the generation of the ABE was affected by the frequency of action responses, indicating that the boosting effect from the target decision is robust in the ABE, and the action and the target decision work together in the generation of the ABE. Accordingly, we propose the dynamic trade-off model, arguing that the AIME at different frequencies dynamically trade-off against the boosting effect of target decisions and thus influence the ABE.