Grounding the Attentional Boost Effect in Events and the Efficient Brain

The attentional boost effect in free recall dynamics

With the attentional boost effect (ABE), responding to a briefly presented target in a detection task enhances the encoding of other items presented at the same time. However, the effects of target detection on context memory for the event in which the stimulus appeared remain unclear. Here, we present findings from verbal free recall and recognition experiments that test the effects of target detection during encoding on temporal and relational aspects of context memory. Consistent with prior demonstrations of limited effects of target detection on context memory, in Experiment 1 there was no evidence that target detection influenced the likelihood of transitioning to items that were presented at similar times during encoding, or that were in the same encoding condition. These null effects were replicated in a second experiment, which added an old/new recognition and relational memory test. These results indicate that target detection during encoding has minimal effects on the formation of temporal associations between words in memory.

The effect of target detection on memory retrieval

Attention and memory are fundamental cognitive processes that closely interact. In the attentional boost effect (ABE), the stimuli that co-occur with targets are remembered better than those that co-occur with distractors in target detection tasks performed during memory encoding. In target detection tasks performed during retrieval, the stimuli that co-occur with targets are recognized as 'old' more easily than the stimuli that co-occur with distractors. This study mainly explored the internal mechanism of the effect of target detection on recognition. In Experiment 1, the full attention (FA; where participants performed only the memory task) condition was used to compare with divided attention (DA; where participants performed target detection while performing memory retrieval) condition to explore the impact of target detection and distraction inhibition on recognition. In Experiment 2, the proportion of old and new words in the retrieval stage was adjusted to 1:1 to eliminate the possible reaction tendency caused by the high proportion of old words. In Experiment 3, the presentation time of words was extended to 1.5 s and 3 s to eliminate the possible impact of rapid processing. The results indicated that the effect of target detection on recognition was attributed to both target detection and distraction rejection and is not affected by the ratio of old and new words and the word presentation time. The effect of target detection on recognition may be owing to temporal yoking of the dual tasks, which is different from the effect of target detection on memory encoding.

The generality of the attentional boost effect for famous, unfamiliar, and inverted faces

Familiarity and face inversion not only affect face recognition and memory but also influence attention. Face processing is less attention-demanding for familiar than for unfamiliar faces and for upright than for inverted faces. The automaticity raises the question of how face processing interacts with an increase in attention. Using a dual-task paradigm, we tested the interaction between attention and face familiarity and orientation. Participants encoded a series of faces to memory while simultaneously monitoring a stream of colored squares, pressing the space bar for target-colored squares and making no response to distractor-colored squares. Replicating previous findings of the attentional boost effect (ABE), we found that faces encoded with target squares were better remembered than faces encoded with distractor squares. If the automatic nature of familiar (or upright) face processing makes attention unnecessary, then the attentional boost should be attenuated for familiar relative to unfamiliar faces and for upright relative to inverted faces. Data from three experiments showed, however, that the ABE was the same for all types of faces. These results suggest that target detection did not simply elevate attention in an early encoding phase. Rather, selecting targets and rejecting distractors in the color task may have led to yoked temporal selection of target-concurrent faces for entry into memory.

The attentional boost effect reflects both enhanced memory for target-paired objects and impaired memory for distractor-paired objects

Throughout prolonged tasks, visual attention fluctuates temporally in response to the present stimuli, task demands, and changes in available attentional resources. This temporal fluctuation has downstream effects on memory for stimuli presented during the task. Researchers have established that detection of a target (e.g., a square of a color to which participants are instructed to respond with a button press) within a rapid serial visual presentation (RSVP) stream leads to better memory for concurrently presented stimuli than for stimuli presented along with an RSVP distractor (e.g., a square of a color to which participants are instructed to withhold response). Although debates have arisen regarding whether this memory difference, termed the attentional boost effect, results from target-induced enhancement, distractor-induced impairment, or a combination of the two, researchers have largely come to focus on explanations that consider only target-induced memory enhancement. In the present study, we show across three large-sampled experiments a consistent appearance of both target-induced memory enhancement and distractor-induced memory impairment relative to a baseline. In each experiment, participants responded with a spacebar press to squares of one color in an RSVP stream while withholding response to squares of another color and trials with no square (baseline trials). They simultaneously memorized concurrently presented objects. The presence of both enhancement and impairment in these experiments invites the development of new dual-task research that considers distractor-induced memory impairment and the control of temporal selection across tasks. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Exploring the roles of distinctiveness and performance anticipation in the Attentional Boost Effect

We tested the validity of two alternative accounts of the Attentional Boost Effect (ABE) - the finding that words associated with to-be-responded targets are recognized better than words associated with to-be-ignored distractors. The distinctiveness hypothesis assumes that, during recognition, participants probe their memories for distinctive information confirming that a word was studied (e.g., "I remember having pressed the spacebar, so I must have studied the word"). This strategy cannot be used in a between-subjects condition in which participants cannot appreciate the differences between target - and distractor-paired words. In agreement, Experiments 1A and 1B found that the ABE was significant in a within-subjects design, whereas it was eliminated in a between-subjects design. On the other hand, the performance anticipation hypothesis assumes that, during the study phase, participants anticipate the need of responding to a subset of target-paired words: this would create a persistent performance anticipation that would prevent them from effectively encoding distractor-paired words. In contrast with this account, we found that, when blocks of five distractor trials were regularly alternated with blocks of five target trials in Experiment 2, recognition accuracy decreased linearly in both conditions. Overall, these results suggest that distinctiveness, but not performance anticipation, might underlie the ABE.

The attentional boost effect overcomes dual-task interference in choice-response tasks

Dual-task interference often arises when people respond to an incoming stimulus according to an arbitrary rule, such as choosing between the gas pedal and the brake when driving. Severe interference from response selection yields a brief "Psychological Refractory Period," during which a concurrent task is put on hold. Here, we show that response selection in one task does not always hamper the processing of a secondary task. Responding to a target may paradoxically enhance the processing of secondary tasks, even when the target requires complex response selection. In three experiments, participants encoded pictures of common objects to memory while simultaneously monitoring a rapid serial visual presentation (RSVP) of characters or colours. Some of the RSVP stimuli were targets, requiring participants to press one of the two buttons to report their identity; others were distractors that participants ignored. Despite the increased response selection demands on target trials, pictures encoded with the RSVP targets were better remembered than those encoded with the RSVP distractors. Contrary to previous reports and predictions from dual-task interference, the attentional boost from target detection overcomes increased interference from response selection.

Attention-dependent coupling with forebrain and brainstem neuromodulatory nuclei changes across the lifespan

Attentional states continuously reflect the predictability and uncertainty in one's environment having important consequences for learning and memory. Beyond well known cortical contributions, rapid shifts in attention are hypothesized to also originate from deep nuclei, such as the basal forebrain (BF) and locus coeruleus (LC) neuromodulatory systems. These systems are also the first to change with aging. Here we characterized the interplay between these systems and their regulation of afferent targets - the hippocampus (HPC) and posterior cingulate cortex (PCC) - across the lifespan. To examine the role of attentional salience on task-dependent functional connectivity, we used a target-distractor go/no go task presented during functional MRI. In younger adults, BF coupling with the HPC, and LC coupling with the PCC, increased with behavioral relevance (targets vs distractors). Although the strength and presence of significant regional coupling changed in middle age, the most striking change in network connectivity was in old age, such that in older adults BF and LC coupling with their cortical afferents was largely absent and replaced by stronger interconnectivity between LC-BF nuclei. Overall rapid changes in attention related to behavioral relevance revealed distinct roles of subcortical neuromodulatory systems. The pronounced changes in functional network architecture across the lifespan suggest a decrease in these distinct roles, with deafferentation of cholinergic and noradrenergic systems associated with a shift towards mutual support during attention guided to external stimuli.

Target detection does not influence temporal memory

Target detection has been found to enhance memory for concurrently presented stimuli under dual-task conditions. This "attentional boost effect" is reminiscent of findings in the event memory literature, where conditions giving rise to event boundaries have been shown to enhance memory for boundary items. Target detection commonly requires a working memory update (e.g., adding to a covert mental target count), which is also thought to be a key contributor to creating event boundaries. However, whether target detection impacts temporal memory in similar ways as event boundaries remains unknown, because these two parallel literatures have used different types of memory tests, making direct comparisons difficult. In a preregistered experiment with sequential Bayes factor design, we examined whether target detection influences temporal binding between items by inserting target and nontarget stimuli during encoding of trial-unique object images, and then comparing subsequent temporal order and distance memory for image pairs that span a target or nontarget. We found that target detection enhanced recognition memory for target trial images but had no effect on temporal binding between items. In a follow-up experiment, we showed that when the encoding task required updating of task set rather than target count, event segmentation-related temporal memory effects were observed. These results document that target detection as such does not disrupt inter-item associations in memory, and that attention orienting in the absence of updating task sets does not create event boundaries. This suggests a key distinction between declarative and procedural working memory updates in segmenting events in memory.

Can divided attention at retrieval improve memory? Effects of target detection during recognition

The attentional boost effect (ABE) is an improvement of memory under divided attention conditions in which stimulus encoding is enhanced when a target is detected in a simultaneous target-monitoring distracting task. Here we asked whether memory is similarly improved when the target-monitoring task occurs at the time of retrieval. In four experiments, participants encoded words under full attention then completed a recognition test under either divided attention, during which participants made recognition judgments while performing the target-monitoring task, or full attention, in which the target-monitoring task was not performed. Relative to distractor rejection, target detection increased hits and false alarms under divided attention with no net effect on discrimination. Targets and distractors had no effect on recognition under full attention. The target-related increase in hits and false alarms occurred regardless of whether the target-monitoring material matched or mismatched the test material and regardless of the target-to-distractor ratio and the target response. A change in bias accounts for the phenomenon, in which participants adopt a more lenient criterion for target-paired words than for distractor-paired words. The same divided attention manipulation that enhances memory at encoding does not similarly enhance memory at retrieval. Theoretical explanations are discussed.

The role of alerting in the attentional boost effect

Stimuli presented simultaneously with behaviorally relevant events (e.g., targets) are better memorized, an unusual effect defined as the attentional boost effect (ABE). We hypothesized that all types of behaviorally relevant events, including attentional cues, can promote the encoding process for the stimuli paired with them, and the attentional alerting network can amplify the ABE. The two experiments we conducted demonstrated that not all behaviorally relevant events, including alerting cues, benefit the processing of concurrently paired stimuli. We also found that the presence of a cue prior to a target can extend the memory advantage produced by target detection, but this advantage can only be observed within a limited range of time. Overall, our study provides the first evidence that the alerting network plays an important role in the ABE.