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.

Effects of divided attention at encoding and retrieval: Further data

Division of attention (DA) at the time of learning has large detrimental effects on subsequent memory performance, but DA at retrieval has much smaller effects (Baddeley, Lewis, Eldridge, & Thomson, 1984, Journal of Experimental Psychology: General, 113, 518-540; Craik, Govoni, Naveh-Benjamin, & Anderson, 1996, Journal of Experimental Psychology: General, 125, 159-180). Experiment 1 confirmed the relatively small effects of DA on retrieval and also showed that retrieval operations do consume processing resources. The experiment also found that the effect is not attributable to a trade-off in performance with the concurrent task or to recognition decisions made on the basis of familiarity judgments. Participants made levels-of-processing (LOP) judgments during encoding to check whether deeper semantic judgments were differentially vulnerable to the effects of DA. In fact DA did not interact with LOP. Experiment 2 explored reports that the comparatively slight effect of DA on recognition accuracy is accompanied by a compensatory increase in recognition latency (Baddeley et al., 1984). The experiment replicated findings that neither DA nor differential emphasis between recognition and a concurrent continuous reaction time (CRT) task affected recognition accuracy, but also found evidence for a lawful trade-off in decision latencies between recognition and CRT performance. Further analysis showed that the relationship between response rates on the two tasks was well described by a linear function, and that this function was demonstrated by the majority of individual participants. It is concluded that the small effect of DA on recognition performance is attributable to a trade-off within the recognition task itself; accuracy is maintained by a compensatory increase in decision latency.

Being observed caused physiological stress leading to poorer face recognition

Being observed when completing physical and mental tasks alters how successful people are at completing them. This has been explained in terms of evaluation apprehension, drive theory, and due to the effects of stress caused by being observed. In three experiments, we explore how being observed affects participants' ability to recognise faces as it relates to the aforementioned theories - easier face recognition tasks should be completed with more success under observation relative to harder tasks. In Experiment 1, we found that being observed during the learning phase of an old/new recognition paradigm caused participants to be less accurate during the test phase than not being observed. Being observed at test did not affect accuracy. We replicated these findings in an line-up type task in Experiment 2. Finally, in Experiment 3, we assessed whether these effects were due to the difficulty of the task or due to the physiological stress being observed caused. We found that while observation caused physiological stress, it did not relate to accuracy. Moderately difficult tasks (upright unfamiliar face recognition and inverted familiar face recognition) were detrimentally affected by being observed, whereas easy (upright familiar face recognition) and difficult tasks (inverted unfamiliar face recognition) were unaffected by this manipulation. We explain these results in terms of the direct effects being observed has on task performance for moderately difficult tasks and discuss the implications of these results to cognitive psychological experimentation.

Memory Performance for Everyday Motivational and Neutral Objects Is Dissociable from Attention

Episodic memory is typically better for items coupled with monetary reward or punishment during encoding. It is yet unclear whether memory is also enhanced for everyday objects with appetitive or aversive values learned through a lifetime of experience, and to what extent episodic memory enhancement for motivational and neutral items is attributable to attention. In a first experiment, we investigated attention to everyday motivational objects using eye-tracking during free-viewing and subsequently tested episodic memory using a remember/know procedure. Attention was directed more to aversive stimuli, as evidenced by longer viewing durations, whereas recollection was higher for both appetitive and aversive objects. In the second experiment, we manipulated the visual contrast of neutral objects through changes of contrast to further dissociate attention and memory encoding. While objects presented with high visual contrast were looked at longer, recollection was best for objects presented in unmodified, medium contrast. Generalized logistic mixed models on recollection performance showed that attention as measured by eye movements did not enhance subsequent memory, while motivational value (Experiment 1) and visual contrast (Experiment 2) had quadratic effects in opposite directions. Our findings suggest that an enhancement of incidental memory encoding for appetitive items can occur without an increase in attention and, vice versa, that enhanced attention towards salient neutral objects is not necessarily associated with memory improvement. Together, our results provide evidence for a double dissociation of attention and memory effects under certain conditions.

Recognition memory for distractor faces depends on attentional load at exposure

Incidental recognition memory for faces previously exposed as task-irrelevant distractors was assessed as a function of the attentional load of an unrelated task performed on superimposed letter strings at exposure. In Experiment 1, subjects were told to ignore the faces and either to judge the color of the letters (low load) or to search for an angular target letter among other angular letters (high load). A surprise recognition memory test revealed that despite the irrelevance of all faces at exposure, those exposed under low-load conditions were later recognized, but those exposed under high-load conditions were not. Experiment 2 found a similar pattern when both the high- and low-load tasks required shape judgments for the letters but made differing attentional demands. Finally, Experiment 3 showed that high load in a nonface task can significantly reduce even immediate recognition of a fixated face from the preceding trial. These results demonstrate that load in a nonface domain (e.g., letter shape) can reduce face recognition, in accord with Lavie's load theory. In addition to their theoretical impact, these results may have practical implications for eyewitness testimony.

Representation of unattended material in memory

The current study addresses how information whose processing was not part of task requirement (unattended) is represented in memory. Using a novel measure, recognition memory for unattended material was assessed twice, once when it appeared with the same (old) attended study target and once with a new target. The data reveal memory for unattended study information only in the old target condition. Results suggest that the entire study event is encoded and represented in a memory trace, which contains both attended target information along with unattended context information. In conclusion, manifestation of unattended memory may be dependent on the presence of old target information at test.

Collaborative memory and part-set cueing impairments: the role of executive depletion in modulating retrieval disruption

When people are exposed to a subset of previously studied list items they recall fewer of the remaining items compared to a condition where none of the studied items is provided during recall. This occurs both when the subset of items is provided by the experimenter (i.e., the part-set cueing deficit in individual recall) and when they are provided during the course of a collaborative discussion (i.e., the collaborative inhibition effect in group recall). Previous research has identified retrieval disruption as a common mechanism underlying both effects; however, less is known about the factors that may make individuals susceptible to such retrieval disruption. In the current studies we tested one candidate factor: executive control. Using an executive depletion paradigm we directly manipulated an individual's level of executive control during retrieval. Results revealed no direct role of executive depletion in modulating retrieval disruption. In contrast, executive control abilities were indirectly related to retrieval disruption through their influence at encoding. Together these results suggest that executive control des not directly affect retrieval disruption at the retrieval stage, and that the role of this putative mechanism may be limited to the encoding stage.

Focusing on food during lunch enhances lunch memory and decreases later snack intake

We investigated whether eating lunch mindfully, in contrast to eating with distractions or no particular focus, reduces later snack intake and if this is related to a measure of meal memory. The design was between-subjects with three conditions. Twenty-nine female undergraduate students either ate a fixed lunch while (1) focusing on the sensory characteristics of the food as they ate (food focus group), (2) reading a newspaper article about food (food thoughts control group) or (3) in the absence of any secondary task (neutral control group). Cookie intake later that afternoon was measured as well as rated vividness of memory of the lunch. Participants ate significantly fewer cookies in the food focus group than in both the food thoughts control group or the neutral control group. Rated appetite before the snack session was lower in the food focus group than in the other two groups and rated vividness of lunch memory was higher. Rated vividness of lunch memory was negatively correlated with snack intake. These results suggest that enhancing meal memory by paying attention to food while eating can reduce later intake and are consistent with the suggestion that memory plays an important role in appetite control.

Effects of task-set adoption on ERP correlates of controlled and automatic recognition memory

Successful memory retrieval depends not only on memory fidelity but also on the mental preparedness on the part of the subject. ERP studies of recognition memory have identified two topographically distinct ERP components, the FN400 old/new effect and the late posterior component (LPC) old/new effect, commonly associated with familiarity and recollection, respectively. Here we used a task-switching paradigm to examine the extent to which adoption of a retrieval task-set influences FN400 and LPC old/new effects, in light of the presumption that recollection, as a control process, relies on the adoption of a retrieval task-set, but that familiarity-based retrieval does not. Behavioral accuracy indicated that source memory (experiment 2), but not item recognition (experiment 1), improved with task-set adoption. ERP data demonstrated a larger LPC on stay trials when a task-set had been adopted even with a simple recognition memory judgment. We conclude that adopting a retrieval task-set impacts recollection memory but not familiarity. These data indicate that attentional state immediately prior to retrieval can influence objective measures of recollection memory.

Television watching during lunch increases afternoon snack intake of young women

Eating while watching television has been shown to increase food intake in part due to the distracting effects of television viewing. It is also known that enhancing memory for the specific attributes of foods eaten in the recent past decreases subsequent food intake. Because distraction at the time of encoding interferes with memory formation, we predicted that television watching during lunch would increase afternoon snack intake due to impaired memory for recent eating. Using a repeated-measures design, 16 young women undergraduate students visited the laboratory to eat a fixed lunch either while watching television or in the absence of television. Intake of cookies at a tasting session later that afternoon was measured and participants recalled eating the lunch and rated the memory for vividness. All participants ate all of the lunch and rated appetite during lunch did not differ according to condition. Participants ate significantly more cookies after they had eaten their lunch while watching television than when they had eaten their lunch while not watching television and this effect could not be attributed to an effect of television watching on rated mood or appetite before the snack session. Watching television while eating lunch was also associated with reduced vividness ratings of the memory of the lunch. These results suggest that the effects of television watching on food intake extend beyond the time of television watching to affect subsequent consumption. They further suggest that this effect may be related to an effect of television watching on encoding of the memory of the meal.

Fractionation of the component processes underlying successful episodic encoding: a combined fMRI and divided-attention study

Considerable evidence suggests that attentional resources are necessary for the encoding of episodic memories, but the nature of the relationship between attention and neural correlates of encoding is unclear. Here we address this question using functional magnetic resonance imaging and a divided-attention paradigm in which competition for different types of attentional resources was manipulated. Fifteen volunteers were scanned while making animacy judgments to visually presented words and concurrently performing one of three tasks on auditorily presented words: male/female voice discrimination (control task), 1-back voice comparison (1-back task), or indoor/outdoor judgment (semantic task). The 1-back and semantic tasks were designed to compete for task-generic and task-specific attentional resources, respectively. Using the "remember/know" procedure, memory for the study words was assessed after 15 min. In the control condition, subsequent memory effects associated with later recollection were identified in the left dorsal inferior frontal gyrus and in the left hippocampus. These effects were differentially attenuated in the two more difficult divided-attention conditions. The effects of divided attention seem, therefore, to reflect impairments due to limitations at both task-generic and task-specific levels. Additionally, each of the two more difficult divided-attention conditions was associated with subsequent memory effects in regions distinct from those showing effects in the control condition. These findings suggest the engagement of alternative encoding processes to those engaged in the control task. The overall pattern of findings suggests that divided attention can impact later memory in different ways, and accordingly, that different attentional resources, including task-generic and task-specific resources, make distinct contributions to successful episodic encoding.

Contribution of frontal and temporal lobe function to memory interference from divided attention at retrieval

On the basis of their scores on composite measures of frontal and temporal lobe function, derived from neuropsychological testing, seniors were divided preexperimentally into 4 groups. Participants studied a list of unrelated words under full attention and recalled them while concurrently performing an animacy decision task to words, an odd-digit identification task to numbers, or no distracting task. Large interference effects on memory were produced by the animacy but not by the odd-digit distracting task, and this pattern was not influenced by level of frontal or temporal lobe function. Results show associative retrieval is largely disrupted by competition for common representations, and it is not affected by a reduction in general processing resources, attentional capacity, or competition for memory structures in the temporal lobe.

Asymmetry between encoding and retrieval processes: evidence from divided attention and a calibration analysis

Two experiments provide further information on the effects of divided attention (DA) on encoding and retrieval processes. The first experiment examined the effects of decision and motor difficulty of a concurrent reaction time task. A calibration analysis was used in the second experiment to test the hypothesis that shifting attentional emphasis away from encoding to the secondary task reduces the level of processing the to-be-remembered items receive. Overall, the results confirm and extend the conclusions of Craik, Govoni, Naveh-Benjamin, and Anderson (1996) and Naveh-Benjamin, Craik, Guez, and Dori (1998), by pointing to clear differences between encoding and retrieval processes: Encoding is affected by simultaneous task demands, especially those associated with "central" resources involved in conscious decision making, whereas retrieval is obligatory in that it is largely immune to the effects of simultaneous demands. The results of the calibration analysis suggest that one reason for the poorer memory performance as a result of DA at encoding is a qualitative shift to less deep, elaborative strategies.

The effects of divided attention on encoding and retrieval processes: the resiliency of retrieval processes

We have recently cast doubt (Craik, Govoni, Naveh-Benjamin, & Anderson, 1996; Naveh-Benjamin, Craik, Guez, & Dori, 1998) on the view that encoding and retrieval processes in human memory are similar. Divided attention at encoding was shown to reduce memory performance significantly, whereas divided attention at retrieval affected memory performance only minimally. In this article we examined this asymmetry further by using more difficult retrieval tasks, which require substantial effort. In one experiment, subjects had to encode and retrieve lists of unfamiliar name-nouns combinations attached to people's photographs, and in the other, subjects had to encode words that were either strong or weak associates of the cues presented with them and then to retrieve those words with either intra- or extra-list cues. The results of both experiments showed that unlike division of attention at encoding, which reduces memory performance markedly, division of attention at retrieval has almost no effect on memory performance, but was accompanied by an increase in secondary-task cost. Such findings again illustrated the resiliency of retrieval processes to manipulations involving the withdrawal of attention. We contend that retrieval processes are obligatory or protected, but that they require attentional resources for their execution.