Building Search Terms That Detect Implicit Manifestations of Prospective Memory Even When the Phenomenon Is Not Named Explicitly

 

 

 

 

 

 

 

Building Search Terms That Detect Implicit Manifestations of Prospective Memory Even When the Phenomenon Is Not Named Explicitly

Analytical Research Report

8 April 2026

 

Abstract

This report analyzes how search terms can be constructed to identify implicit manifestations of prospective memory (PM) when the phenomenon is described without using the explicit label “prospective memory.” In this context, an implicit manifestation refers to a description of remembering to carry out a delayed intention at an appropriate later moment, even if the source instead speaks of forgetting a promised action, noticing a cue, remembering at the right time, missing a deadline, or relying on reminders, checklists, or other supports. The report distinguishes the conceptual core of PM from neighboring constructs such as retrospective memory, planning, reminders, task management, routines, and external memory aids. The analysis argues that effective retrieval usually requires combining at least four complementary search directions: action descriptions, situation or context descriptions, problem or error descriptions, and substitute or adjacent concepts. It further argues that single theory terms are often too narrow, whereas paraphrases, example sentences, event chains, and behavior descriptions can recover relevant material that would otherwise be missed. However, broader retrieval raises the risk of false positives because many descriptions of planning, memory, scheduling, and productivity do not involve delayed-intention retrieval. For that reason, the report proposes an explicit screening logic centered on three minimal criteria: prior intention, delay interval, and later cue- or time-appropriate execution opportunity. Methodologically, the strongest conclusion is not that search terms alone can solve the problem, but that they can substantially improve recall when embedded in an iterative process involving seed articles, synonym expansion, controlled vocabulary, citation chaining, peer review, and a coding framework for relevance decisions. The report concludes that search-term construction for implicit PM is feasible, but only under conditions of explicit conceptual delimitation and systematic validation.

Keywords: prospective memory, information retrieval, search strategy, implicit concepts, delayed intentions, recall and precision

 

Table of Contents

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1. Introduction

Prospective memory (PM) is commonly defined as memory for delayed intentions: remembering to perform an intended action at an appropriate future moment rather than remembering past information as such. In the literature, this future action can be triggered by a time point, an external event, or the completion of another activity. The central practical difficulty for literature searching is that many relevant descriptions do not use the label “prospective memory” even when they describe the phenomenon. A source may instead describe remembering to send a document later, forgetting to take medication, missing a deadline, noticing a contextual cue and then acting, or relying on a reminder system because one must remember to act in the future. Those cases may instantiate PM conceptually while remaining invisible to narrow theory-term searches.

The present report addresses the following research problem: how should search terms be built to retrieve implicit manifestations of PM when the phenomenon is not explicitly named? The question matters methodologically because a search that depends mainly on the explicit label “prospective memory” will produce false negatives, whereas a search broadened to everyday descriptions such as “remember to” or “forget to” may produce an unmanageable number of false positives. The task is therefore not only to maximize recall but to do so without dissolving the concept into generic talk about memory, planning, reminders, or productivity.

The report proceeds analytically rather than experimentally. It synthesizes PM theory and literature-search methodology in order to propose a defensible framework for term construction, screening, and iterative refinement. Throughout, observations, interpretations, and more speculative extrapolations are kept separate where possible.

 

2. Theoretical Background / Previous Research

2.1 Prospective memory as a cognitive phenomenon

A stable point across the PM literature is that the phenomenon concerns delayed intentions. In other words, the individual must (a) form an intention, (b) retain that intention across a delay while engaging in other activity, and (c) retrieve and execute the intention when the appropriate opportunity arises. Reviews and theoretical papers further distinguish event-based PM, time-based PM, and often activity-based PM. Event-based tasks depend on a relevant cue in the environment; time-based tasks depend more strongly on self-initiated monitoring of time; activity-based tasks are executed after the completion of another activity (Blondelle et al., 2022; Gonneaud et al., 2014; McDaniel et al., 2015).

A second important finding is that PM is not supported by a single retrieval mechanism. The dynamic multiprocess perspective argues that delayed intentions may be supported by a mixture of strategic monitoring and cue-driven spontaneous retrieval, with task properties shaping which process dominates. Cue focality, contextual regularity, and expectations about when the cue will occur all matter for whether the individual must actively monitor or can rely more on cue-triggered retrieval (McDaniel et al., 2015; Scullin et al., 2013). This matters for search design because implicit manifestations may be described in language that highlights either strategic monitoring (“keep checking the time,” “keep this in mind”) or cue-triggered realization (“when she saw the invoice, she remembered to send the form”).

A third important line of work treats PM as phased rather than monolithic. Lifespan and neuropsychological research often distinguishes intention formation, retention, initiation, and execution. This phase structure is useful for search construction because relevant texts may describe breakdowns or supports at different points: poorly specified intentions, failure to maintain them, missing initiation at the right moment, or incomplete execution after recall (Kliegel et al., 2008).

2.2 The conceptual core versus neighboring constructs

The concept must be delimited carefully. PM overlaps with several neighboring constructs, but it is not identical to them.

Retrospective memory concerns remembering previously encountered information, whereas PM concerns remembering that something must be done later. The two interact because one may remember that an intention exists yet fail to remember its content, or remember the content yet fail to act at the right time. However, retrieving past information alone does not constitute PM.

Planning is also not sufficient. A person may plan extensively without any later retrieval demand. PM becomes relevant when an already formed intention must later be reinstated and acted upon under delayed conditions.

Reminding and reminders are likewise adjacent but not identical. A reminder can support PM, but a text about reminders may focus on device design, calendar use, or notification preferences without discussing delayed-intention retrieval itself. Similarly, task management, scheduling, and checklists may externalize PM demands, but not every discussion of such tools is conceptually about PM.

Routines are especially tricky. A highly automatized routine can resemble PM behaviorally, yet strongly habitual action may no longer require the same prospective retrieval processes. For retrieval purposes, routine descriptions should therefore be treated as peripheral unless the text clearly concerns remembering to carry out an intention under a delayed and potentially interruptible condition.

2.3 What counts here as an implicit manifestation of prospective memory?

In this report, an implicit manifestation of PM means a textual description that satisfies the conceptual core of PM without naming the construct explicitly. The minimum criteria are: (1) a prior intention or obligation is implied; (2) there is a delay interval between intention formation and relevant opportunity for action; and (3) the later action is expected to occur when a time, event, or activity cue becomes relevant.

On this basis, statements such as “he forgot to submit the form before the deadline,” “she remembered to call when she arrived home,” or “the nurse relies on a checklist so the medication task is not missed during the shift” are potentially implicit manifestations. By contrast, statements such as “people often forget names,” “the team planned next quarter’s goals,” or “the app improves productivity” would not count unless the delayed-intention structure is also present.

 

3. Method

3.1 Material and data

The report is based on targeted scholarly literature concerning PM theory and literature-search methodology. The PM side was used to define the conceptual core, task types, retrieval mechanisms, and phase distinctions. The search-method side was used to ground principles of high-sensitivity searching, the combination of free-text and controlled vocabulary, iterative development, peer review, and the trade-off between recall and precision (Bramer et al., 2018; Cooper et al., 2018; DeMars & Perruso, 2022; Lefebvre et al., 2025; McGowan et al., 2016; Zwakman et al., 2018).

3.2 Collection, selection, and delimitation

The analysis is delimited to the problem of conceptual retrieval: how to find relevant texts when terminology varies and the target construct may be expressed indirectly. It does not attempt to provide a validated database-specific filter for all disciplines. Nor does it claim that one universal string would perform equally well across psychology, health care, organization studies, human factors, education, and information systems. Instead, it develops general principles that can be adapted to specific databases and domains.

3.3 Analysis

The analysis proceeded in four steps. First, the conceptual core of PM was distilled into minimal relevance criteria: prior intention, delay, and later appropriate execution opportunity. Second, adjacent but broader constructs were mapped in order to identify likely false-positive regions: general memory, planning, reminders, task management, routines, and productivity discourse. Third, candidate search-term families were organized into four directions: action descriptions, situation or context descriptions, problem or error descriptions, and substitute or adjacent concepts. Fourth, the likely effects of broad versus narrow query design were evaluated using standard information-retrieval reasoning about recall, precision, false positives, and false negatives. This led to an iterative validation framework rather than a one-shot search-string solution.

3.4 Reliability and validity

Reliability in this report rests on conceptual transparency: the criteria for what counts as PM are made explicit, and the report separates stronger from weaker inferences. Validity depends on whether the proposed search logic actually retrieves texts whose substantive content matches PM rather than merely nearby themes. Because no full-scale database benchmarking was conducted here, external validation remains incomplete. The conclusions should therefore be read as a theoretically grounded methodological framework, not as a fully validated retrieval filter.

 

4. Results

4.1 Why theory terms alone are insufficient

Observation. The explicit term “prospective memory” is only one lexical surface form for a wider phenomenon. PM research itself often explains the construct using examples such as remembering to post a letter, take medication, call someone later, or act when a target cue appears. Everyday and applied literatures may retain those descriptions while omitting the theory label.

Interpretation. A search that relies mainly on “prospective memory” risks high conceptual specificity but low coverage of applied or non-psychological discussions. This is especially likely in professional literatures where authors describe workflow failures, missed deadlines, or reliance on reminders without translating them into cognitive terminology.

Speculation. The problem may be strongest in interdisciplinary corpora such as management, nursing, human-computer interaction, education, and safety studies, where the behavior is described functionally rather than theoretically.

The most defensible conclusion is therefore that search strings should be built from multiple representational layers, not from one theory term alone.

4.2 Four directions for constructing search terms

4.2.1 Direction 1: Action descriptions

Action-description terms aim to capture what people are trying to remember to do. The advantage is ecological closeness: many implicit PM texts describe behavior rather than theory. Candidate patterns include “remember to,” “forgot to,” “failed to,” “meant to,” “intended to,” “was supposed to,” “planned to do later,” “carry out an intention,” and “execute a delayed intention.” These phrases become more useful when joined to later-action markers such as send, call, submit, take, bring, check, attend, lock, reply, deliver, and renew. In domain-specific corpora, action verbs should be customized.

4.2.2 Direction 2: Situation or context descriptions

Situation terms target the structural conditions under which PM occurs. Useful patterns include after a delay, later on, at the right time, when the time comes, when a cue appears, upon arrival, before the deadline, during an ongoing task, while doing something else, after finishing the current task, and in response to a cue. These expressions reflect common PM paradigms: ongoing-task interference, cue detection, and delayed execution.

4.2.3 Direction 3: Problem or error descriptions

Many applied texts describe PM implicitly through failure rather than success. Candidate terms include forgetting intended actions, intention failure, missed deadline, omitted intended action, failure to remember to act, prospective lapse, action omission, missed appointment, forgot medication, forgot to submit, forgot to call, and absent-minded omission. These expressions are often more revealing in safety-critical or clinical literature, where failures are documented as incidents, adherence problems, or everyday lapses.

4.2.4 Direction 4: Substitute or adjacent concepts

A fourth strategy is to search for neighboring concepts that sometimes substitute for PM or partially overlap with it. Relevant candidates include delayed intentions, intention retrieval, cue-triggered remembering, future-oriented remembering, remembering future tasks, memory for intentions, cue-action association, implementation intentions, time monitoring, reminder use, external memory aids, and intention maintenance. This direction is valuable because some texts discuss a process that supports PM, such as time monitoring or implementation intentions, rather than PM as a whole, but it also carries the greatest risk of conceptual drift.

Table 1. Search-term construction directions, strengths, and risks

Direction	Illustrative terms	Strength	Main risk
Action descriptions	remember to; forgot to; intended to; was supposed to	High ecological recall	Very broad everyday language
Situation/context	after a delay; upon arrival; before deadline; while doing another task	Closer to PM structure	Can drift into generic scheduling
Problem/error	missed appointment; forgot medication; action omission	Good for applied literature	Can collapse into generic error or noncompliance
Adjacent concepts	delayed intentions; time monitoring; reminder use	Useful for expansion	Highest conceptual drift

4.3 Why paraphrases, example sentences, event chains, and behavior descriptions often outperform isolated theory terms

Observation. PM is frequently communicated in narratives or examples: “remember to give a message when you see the person,” “take medication at 8 p.m.,” or “reply to the email after the meeting.” Such phrasings encode the phenomenon more concretely than abstract theory labels.

Interpretation. Query expansion should therefore include paraphrases and event chains. A useful event-chain template is form intention -> engage in other activity -> encounter time/event/activity cue -> retrieve intention -> execute action. Search terms can be built from each segment of this chain, which improves recall because it captures descriptions that do not use theoretical vocabulary.

This chain-based method can also improve screening because retrieved texts can be judged against the full structure rather than a single token.

4.4 High-precision versus high-recall strategies

A high-precision strategy aims to reduce screening burden by requiring stronger conceptual structure in the query. Such a string may combine a PM-like action phrase with a delay or cue phrase. This approach is helpful in large noisy corpora, but it will miss many relevant texts whose wording is less predictable.

A high-recall strategy uses broader synonym families, natural-language paraphrases, controlled vocabulary, and citation chaining. It accepts lower precision in order to reduce false negatives. Cochrane guidance explicitly notes that systematic searches often aim for high sensitivity even at the cost of lower precision, and that broad synonym coverage within each concept is generally preferable to overly restrictive conceptual multiplication (Lefebvre et al., 2025).

The best-supported inference is that implicit-PM searching should usually begin on the recall side and then be narrowed iteratively. Starting with a highly precise string is more likely to miss the very implicit cases that motivate the search problem.

4.5 How false positives and false negatives arise

False positives arise when the search retrieves texts about neighboring but non-equivalent topics, such as generic memory complaints without future action, planning or goal-setting without delayed retrieval, reminder technologies without evidence of intention retrieval, routines and habits that no longer require active prospective remembering, generic human error or noncompliance, and task management discourse. False negatives arise when relevant texts describe PM only through concrete examples, use domain-specific verbs rather than cognitive language, emphasize failure outcomes rather than memory processes, are indexed under adjacent controlled terms, or discuss monitoring, cue detection, or implementation intentions without naming PM.

4.6 Operational criteria for deciding whether a hit is genuinely relevant

To distinguish genuine PM hits from broader discourse, five screening questions are useful: (1) Is there evidence of a prior intention, obligation, or plan? (2) Is there a delay interval during which other activity intervenes? (3) Is the relevant later moment defined by time, event, or activity completion? (4) Is the key issue remembering to act, rather than simply knowing, planning, or complying? (5) If external aids are discussed, are they presented as supports for remembering delayed intentions rather than merely as organizational conveniences? A record should be treated as central if the answer is yes to the first four questions.

4.7 Principles for iterative testing, expansion, narrowing, and validation

First, begin from a small seed set of clearly relevant PM papers and manually extract recurring lexical variants, examples, verbs, and cue descriptions.

Second, combine free-text terms with controlled vocabulary where available. Studies comparing subject headings and text-word searching show trade-offs: controlled vocabulary can improve specificity, whereas text words often improve recall for variant phrasings (DeMars & Perruso, 2022).

Third, test whether the strategy retrieves known relevant papers. Cochrane guidance recommends checking whether key known publications are found, while warning that this test alone is not sufficient because a strategy can be overfit to know

n records (Lefebvre et al., 2025).

Fourth, expand using citation chaining, pearl growing, and iterative conceptual refinement. Methodological papers on systematic searching and complex topics emphasize iterative refinement, citation-based expansion, and transparent documentation of search decisions (Bramer et al., 2018; Cooper et al., 2018; Zwakman et al., 2018).

Fifth, peer review the strategy. PRESS guidance recommends formal peer review of electronic search strategies because errors in conceptual coverage, syntax, spelling, and field use are common and consequential (McGowan et al., 2016).

 

5. Discussion

The central conclusion of this analysis is that implicit manifestations of PM can be searched for, but not by relying on a single lexical shortcut. The most defensible strategy is concept-first and multilayered. One begins by defining what PM is, then searches not only for the label but for behavior descriptions, situational structures, error forms, and nearby concepts that may index the same phenomenon indirectly.

A key implication is that the unit of retrieval should often be the event structure rather than the word. PM is fundamentally about a delayed intention that becomes actionable when a later opportunity arises. Search terms that encode that structure are more likely to generalize across disciplines than terms that merely repeat the canonical label. This is why paraphrases, event chains, and behavior descriptions may outperform isolated theory terms in practice.

At the same time, there is a real danger of conceptual sprawl. The broader the search, the more likely it is to absorb generic planning, reminder use, workflow discourse, and human-error literature. The appropriate response is not to abandon broad searching, but to pair it with a transparent coding framework. In this respect, search design and screening design are inseparable. A search for implicit PM without an explicit relevance rubric will be unstable and hard to reproduce.

5.1 Alternative view: Implicit searching may be too imprecise without a coding framework

A serious counterargument is that searching for implicit manifestations of PM may be methodologically too imprecise unless one first establishes a coding scheme robust enough to identify PM from text manually. This objection is strong. Without a coding framework, broad search terms can easily generate a corpus dominated by near misses. In that case, the search would not be discovering PM so much as generating an undifferentiated set of texts about memory, planning, reminders, and tasks.

This counterargument is persuasive up to a point. It correctly identifies that the search problem is partly a classification problem. However, it does not follow that search-term design is futile. Rather, it implies that search and coding must be co-designed. Search terms can improve recall of candidate material, while coding criteria preserve conceptual validity. Thus, the strongest position is not “terms alone are enough,” nor “terms are useless,” but “terms are useful only within an explicit relevance framework.”

5.2 Alternative explanation: The apparent problem may reflect indexing rather than language

Another possibility is that the main barrier is not implicit language in documents but inconsistent indexing across databases. If that is true, better use of controlled vocabulary, subject headings, and citation chasing could solve more of the problem than expanding natural-language phrases. This explanation has some force, especially in databases with rich indexing. Yet it is incomplete because many interdisciplinary and applied texts either lack precise PM indexing or frame the phenomenon operationally rather than cognitively. Accordingly, controlled vocabulary should be treated as necessary but not sufficient.

 

6. Conclusion

The question posed in this report can be answered cautiously but affirmatively. Search terms can be built to retrieve implicit manifestations of PM even when the term itself is absent, but this requires explicit conceptual delimitation and iterative validation. The conceptual core of PM is the delayed execution of an intention at an appropriate future moment, usually organized around time, event, or activity cues. Search strategies should therefore be built from at least four directions: action descriptions, situation or context descriptions, problem or error descriptions, and substitute or adjacent concepts.

The most reliable practical principle is to search for the structure of the phenomenon, not merely its canonical label. Paraphrases, example sentences, event chains, and behavior descriptions are often better suited than isolated theory terms for finding implicit cases. However, broader searching necessarily increases false positives. The problem is therefore best handled by combining high-recall searching with explicit screening criteria, controlled vocabulary, citation chaining, and formal peer review of the search strategy.

The report’s contribution is conceptual and methodological: it specifies what should count as an implicit manifestation of PM, clarifies how such manifestations differ from neighboring constructs, and proposes a defensible framework for building, testing, and validating search terms. Further research should empirically benchmark alternative strings across databases and disciplines, compare manual coding against automated retrieval, and test whether large-language-model-assisted query expansion improves recall without unacceptable drift in precision.

 

7. References

Blondelle, G., Sugden, N., & Hainselin, M. (2022). Prospective memory assessment: Scientific advances and future directions. Frontiers in Psychology, 13, Article 958458. https://doi.org/10.3389/fpsyg.2022.958458

Bramer, W. M., de Jonge, G. B., Rethlefsen, M. L., Mast, F., & Kleijnen, J. (2018). A systematic approach to searching: An efficient and complete method to develop literature searches. Journal of the Medical Library Association, 106(4), 531-541. https://doi.org/10.5195/jmla.2018.283

Cooper, C., Booth, A., Varley-Campbell, J., Britten, N., & Garside, R. (2018). Defining the process to literature searching in systematic reviews: A literature review of guidance and supporting studies. BMC Medical Research Methodology, 18(1), Article 85. https://doi.org/10.1186/s12874-018-0545-3

DeMars, M. M., & Perruso, C. (2022). MeSH and text-word search strategies: Precision, recall, and their implications for library instruction. Journal of the Medical Library Association, 110(1), 23-33. https://doi.org/10.5195/jmla.2022.1283

Gonneaud, J., Rauchs, G., Groussard, M., Landeau, B., Mézenge, F., de La Sayette, V., Eustache, F., & Desgranges, B. (2014). How do we process event-based and time-based intentions in the brain? An fMRI study of prospective memory in healthy individuals. Human Brain Mapping, 35(7), 3066-3082. https://doi.org/10.1002/hbm.22385

Kliegel, M., Mackinlay, R., & Jäger, T. (2008). Complex prospective memory: Development across the lifespan and the role of task interruption. Developmental Psychology, 44(2), 612-617. https://doi.org/10.1037/0012-1649.44.2.612

Lefebvre, C., Glanville, J., Briscoe, S., Featherstone, R., Littlewood, A., Metzendorf, M.-I., Noel-Storr, A., Paynter, R., Rader, T., Thomas, J., & Wieland, L. S. (2025). Chapter 4: Searching for and selecting studies. In J. P. Higgins, J. Thomas, J. Chandler, M. Cumpston, T. Li, M. J. Page, & V. A. Welch (Eds.), Cochrane handbook for systematic reviews of interventions (Version 6.5.1). Cochrane.

McDaniel, M. A., Umanath, S., Einstein, G. O., & Waldum, E. R. (2015). Dual pathways to prospective remembering. Frontiers in Human Neuroscience, 9, Article 392. https://doi.org/10.3389/fnhum.2015.00392

McGowan, J., Sampson, M., Salzwedel, D. M., Cogo, E., Foerster, V., & Lefebvre, C. (2016). PRESS peer review of electronic search strategies: 2015 guideline statement. Journal of Clinical Epidemiology, 75, 40-46. https://doi.org/10.1016/j.jclinepi.2016.01.021

Scullin, M. K., McDaniel, M. A., & Shelton, J. T. (2013). The dynamic multiprocess framework: Evidence from prospective memory with contextual variability. Cognitive Psychology, 67(1-2), 55-71. https://doi.org/10.1016/j.cogpsych.2013.07.001

Zwakman, M., Verberne, L. M., Kars, M. C., Hooft, L., van Delden, J. J. M., Spijker, R., & van Thiel, G. J. M. W. (2018). Introducing PALETTE: An iterative method for conducting a literature search for a systematic review of complex interventions. BMC Medical Research Methodology, 18(1), Article 82. https://doi.org/10.1186/s12874-018-0547-1

 

Appendix A. Exemplar Term Families for Implicit PM Searching

A.1 Action descriptions

remember to; forgot to; intended to; meant to; was supposed to; carry out intention; execute delayed intention; remember later; forgot later task

A.2 Situation/context descriptions

after a delay; later on; at the right time; when a cue appears; upon arrival; before deadline; while doing another task; after finishing current task; in response to a cue

A.3 Problem/error descriptions

intention failure; omission of intended action; missed appointment; missed deadline; forgot medication; forgot to submit; absent-minded omission

A.4 Adjacent concepts

delayed intentions; memory for intentions; cue-triggered remembering; time monitoring; implementation intentions; reminder use; external memory aids

 

Appendix B. Screening Rubric for Relevance

A record is central to the topic if it satisfies all three conditions: (1) it implies a prior intention or obligation; (2) it includes a delay period before the relevant action opportunity; and (3) the later action depends on remembering to act at a time, event, or activity cue.

A record is peripheral if it discusses reminders, checklists, or task management but does not clearly tie them to delayed-intention retrieval.