Literature Review and Search Strategy
Finding and organizing the literature so your search is reproducible.
Your data is collected, so the literature review now does two jobs. It frames your findings against what the field already knows, and it protects you from the reviewer who asks whether you missed something. Both jobs reward a search you can reproduce and describe, not one you did by memory. This section walks through databases, systematic searching, citation chasing, knowing when to stop, reference management, and how to keep track of everything you read.
The databases that matter for infant emotion research
Each database indexes a different slice of the literature. Searching only one leaves gaps that a committee member will find.
- PsycINFO (APA) is your primary source. It has the deepest coverage of developmental and clinical psychology, and it uses a controlled vocabulary, the Thesaurus of Psychological Index Terms, that lets you search by concept rather than by whatever word an author happened to choose. This is where emotion regulation, temperament, and attachment work lives.
- PubMed / MEDLINE covers the biomedical and neuroscience side. Use it for physiological measures (vagal tone, RSA, cortisol, HPA axis), pediatric samples, and anything published in medical or infancy journals. Its controlled vocabulary is MeSH.
- Web of Science is less about subject coverage and more about citation structure. Its strength is forward citation chasing (the "Times Cited" and "Citing Articles" links) and mapping how a paper has been used since publication. Scopus does the same job if your library has it instead.
- ERIC is the education database. It is worth a pass for early childhood, caregiving, childcare settings, and parent intervention work that psychology databases index thinly.
- Google Scholar is broad and catches preprints, dissertations, book chapters, and gray literature the indexed databases miss. Treat it as a supplement, not a base. It has no controlled vocabulary, no reliable field limits, and its relevance ranking is opaque, so you cannot describe a Scholar search as systematic. Its real value is the "Cited by" link for forward chasing and finding a hard-to-locate full text.
Building a systematic search
A good search is built, not typed. Break your question into concept blocks, usually two to four. For a dissertation on infant emotion regulation, your blocks might be: the population (infants, neonates), the construct (emotion regulation, affect regulation, self-regulation), and possibly a paradigm or measure (still-face, cortisol, vagal tone).
Within each block, list every reasonable synonym and combine them with OR. Then combine the blocks with AND. That is the whole logic.
(infant* OR neonat* OR "early childhood") AND ("emotion regulation" OR "affect regulation" OR "self-regulation" OR "emotional self-regulation") AND ("still-face" OR "vagal tone" OR RSA OR cortisol)Controlled vocabulary versus keywords
Use both, deliberately. Keywords (free-text words in title and abstract) catch brand-new terms and idiosyncratic phrasing. Controlled vocabulary (PsycINFO subject headings, MeSH terms) catches papers regardless of the author's word choice and handles the fact that "affect regulation" and "emotion regulation" are often the same construct. A strong search combines a subject-heading search with a keyword search on the same concept using OR. Look up the exact heading in the database thesaurus rather than guessing.
Truncation and wildcards
infant* retrieves infant, infants, infancy. regulat* retrieves regulate, regulation, regulatory, dysregulation is not caught, so add it. Phrases go in quotation marks so "still-face" is treated as a unit. Note that operators and wildcard symbols differ slightly across platforms, so confirm each one in the database's help before trusting your yield.
Snowballing: chasing citations in both directions
Database searches miss things. Citation chasing catches them, and it is how experienced researchers find the papers everyone in a subfield actually cites.
- Backward snowballing means mining the reference list of a key paper or a recent review. This walks you back toward the foundational work. When you find a strong review or meta-analysis on infant emotion regulation, its reference list is a curated map of the field.
- Forward snowballing means finding everything that has cited a key paper since it was published. This walks you forward to current work and shows you how a construct or measure evolved. Use Web of Science "Citing Articles," Scopus "Cited by," or Google Scholar "Cited by" for this. Connected Papers and Litmaps are visual tools that build a citation network around a seed paper, which is a fast way to spot clusters and the obvious papers you have not read yet.
A practical loop: pick two or three anchor papers you know are central, chase backward from their reference lists and forward from their cited-by lists, add anything relevant to your library, then repeat from the newly added anchors until you stop finding new names.
Knowing when the review is complete enough
You are done when the search is saturated, meaning new searches and new citation chains keep returning papers you already have. The concrete signals:
- The same author names, samples, and instruments recur across independent searches.
- Backward and forward chasing from new anchors surfaces nothing you have not logged.
- You can state the major theoretical positions and the main empirical disagreements without gaps.
Saturation is about the conceptual space being covered, not a paper count. A focused dissertation construct might saturate at 60 well-chosen sources. Document the point where returns flattened so your methods narrative has a defensible stopping rule.
Reference management
Zotero is the recommended tool and it is free and open source. It captures citations from your browser with one click, stores the PDF alongside the record, generates APA 7 references and in-text citations, and plugs into Word or Google Docs. EndNote (paid, often provided through university licenses) and Mendeley are the main alternatives and do the same core job, so if your library already supports one, use it. The tool matters less than using one consistently from the start.
Organizing the library
- Attach the PDF to every record and let Zotero rename files consistently. A folder of "download(3).pdf" files is unusable in a year.
- Use collections for structure (by chapter, by construct, by measure) and tags for cross-cutting attributes a single collection cannot capture, for example
still-face,longitudinal,physiological-measure,to-read,key-paper. - Fix metadata as you import. Zotero pulls author, year, and journal automatically but often mangles capitalization and page ranges, and a bad record produces a bad reference. Clean it once at import, not at 2 a.m. before submission.
Tracking what you read: the synthesis matrix
Reading without a structured record means rereading. Build a synthesis matrix (also called a literature grid), one row per study, with columns you can compare across. A workable set for infant emotion regulation:
- Citation (author, year)
- Sample (n, age, population, recruitment)
- Design (cross-sectional, longitudinal, experimental)
- Measures / paradigm (still-face, RSA, cortisol, observational coding, parent report)
- Key findings
- Limitations and gaps
- Relevance to my study
Read down a column instead of across a row and the review writes itself. The Measures column shows you which paradigms dominate and which are thin. The Gaps column becomes the justification for your own study. A spreadsheet is enough. You do not need special software.
I'm pasting the abstract and methods of a study below. Pull out these fields for my synthesis matrix and return them as a single table row: sample (n, age, population), design, measures or paradigm, key findings, stated limitations. Quote the numbers exactly and mark any field as "not reported" if the text does not state it. [paste text]Narrative review versus systematic review
These are different products and a dissertation can use both in different places.
A narrative review synthesizes and argues. It is selective, organized by theme or theory, and it builds toward your rationale. This is what most dissertation literature chapters are, and it is the right form when your goal is to situate your study and defend your hypotheses. Its rigor comes from fair coverage and honest treatment of contradictory findings, not from an exhaustive protocol.
A systematic review answers a tightly bounded question using a pre-specified, reproducible protocol: defined inclusion and exclusion criteria, documented searches across named databases, screening at title/abstract then full text, and transparent reporting (PRISMA is the standard guideline, and a meta-analysis adds quantitative pooling on top). It fits when a whole chapter or a standalone paper is the systematic review itself, for example "a systematic review of physiological measures of infant emotion regulation."