Memory retrieval often occurs amid distractions. For example, while writing to an acquaintance, you might be reminded that you need to call a colleague. Are you ultimately less likely to remember to make that phone call because you were distracted by other tasks? The results of the present experiments suggest that the answer is yes. Attention is not only necessary during memory encoding (e.g., Baddeley et al., 1984
; Craik et al., 1996
; Mulligan, 1998
), it is also important during memory retrieval to ensure future remembering.
In the present experiments, dividing attention during memory retrieval impaired source memory while impacting item recognition to a lesser extent, supporting the hypothesis that performance on tests that involve effortful contextual retrieval processes suffers under conditions of divided attention (Lozito & Mulligan, 2006
). Furthermore, dividing attention during retrieval increased incorrect source memory responses, yet left the proportion of unsure responses the same, providing further evidence that distraction during retrieval may increase false recollection (Knott & Dewhurst, 2007
; Skinner & Fernandes, 2008
Foils presented on an initial memory test were more likely to be recognized subsequently if they had been encountered under FA versus DA, demonstrating that the negative effects of divided attention during memory encoding can also occur in the context of retrieval. Foils may have been less likely to be encoded under DA, because there were limited encoding resources available. Alternatively, the retrieval processes that were engaged when foils were encountered under DA may have been less likely to be constrained to the recapitulation of study processes, resulting in shallower processing of these foils (Jacoby, Shimizu, Daniels, & Rhodes, 2005
; Jacoby, Shimizu, Velanova, & Rhodes, 2005
). However, because list discrimination did not differ for foils encountered under FA compared with DA, even foils presented under FA may have received relatively little processing during the initial test, or at least little of the type of processing necessary for performing the challenging list discrimination task.
The present data also suggest that dividing attention during memory retrieval is detrimental for subsequent remembering of studied items. Although pictures that were initially tested under DA were more likely to be recognized than pictures that were initially untested, they were not as likely to be recognized as pictures that were initially tested under full attention. Moreover, source memory and list discrimination decisions were superior for pictures that were previously tested under full versus divided attention.
Although it is well established that memory tests are particularly effective study events (for a review, see Roediger & Karpicke, 2006a
), the results of the present experiments support the hypothesis that the power of retrieval as an encoding event is attention dependent. This seems to be true both for item recognition and for source recollection. Importantly, pictures that were recognized on the first test were less likely to be recognized on the second test when attention was divided during initial retrieval. Similarly, when the source of a picture was correctly identified on the first test, this source was less likely to be accurately remembered on the second test if attention had been divided during initial remembering. Because participants were given (and used) an “unsure” option for source memory decisions on both tests, it is unlikely that many of the correct source responses from the initial test reflect guessing or that the observed retrieval benefits can be attributed to the same mnemonic processes that gave rise to better subsequent memory for items that were not accurately recognized on the initial test.
In a follow-up study, we found similar effects using verbal stimuli, suggesting that these effects are not limited to pictorial stimuli. Object names that were initially retrieved under DA were less likely to be retrieved on a later test compared with object names initially retrieved under FA. Similarly, memory for the encoding task, or source memory, was impaired on a second test if it had previously been retrieved under DA versus FA. This replication suggests that the detrimental effects of distraction on future remembering may extend to multiple forms of study materials, highlighting a potential implication for educational situations in which students test themselves on course material under conditions of distraction.
Our results suggest that distraction during memory retrieval disrupts memory processes that give rise to later item recognition and source memory. Recent research has shown that testing enhances subsequent recollection but not familiarity (Chan & McDermott, 2007
), suggesting that divided attention during testing should impair tasks that require recollection to a greater extent than it should impair tasks that rely more on familiarity processes. The relatively deep semantic encoding tasks used in the present experiments likely promoted the role of both recollection and familiarity processes in item recognition (e.g., Hicks & Marsh, 2000
). Future research could elucidate the effects of distraction during memory retrieval on subsequent recollection-versus familiarity-based memories.
Additionally, in the present experiments, re-exposure to studied pictures during the initial memory test may have provided additional opportunities to strengthen item representations that enhanced subsequent familiarity, and this could be true even for items that were accurately retrieved on the initial test. Thus, it is unclear whether the observed decrements in subsequent recognition memory for pictures that were retrieved under DA can be fully accounted for by the effects of DA on memory retrieval processes as opposed to the effects of encoding the second presentation of the picture. However, because source information was not presented during the initial test (it was only retrieved), the decreased likelihood of subsequent source retrieval for pictures previously retrieved under DA suggests that encoding of the second presentation of the pictures cannot fully account for our effects. Future research could further specify the precise conditions under which an initial test affects subsequent item and source memory and could explore the role of attention in these processes.
The results of the present experiments provide novel insight about the power of retrieval as an encoding event, demonstrating that recognition memory and source memory testing benefits are attention dependent. Distractions during memory retrieval reduce the likelihood that a successful act of remembering in the present will support successful remembering in the future, highlighting the importance of attentive remembering for learning.