Synthesizing involves combining perspectives from different sources to generate new insights into your research topic. It requires critically analyzing each source, identifying connections and disconnects, and weaving together complementary concepts or findings into a cohesive narrative.
Example of synthesizing sources
One area extensively explored is the role of age in second language acquisition. Let’s examine how several key sources contribute to this debate:
According to Lenneberg’s influential critical period hypothesis, first proposed in 1967, a finite developmental window exists during which humans can acquire language relatively effortlessly. After puberty, Lenneberg theorized that the neurological capacity for language learning diminishes significantly.
Subsequent research has revisited this claim in the context of second language acquisition. A landmark study by Johnson and Newport (1988) put Lenneberg’s theory to the test, administering grammar assessment tests to Korean and Chinese immigrants who arrived in the United States at different ages. Their data appeared to substantiate a “critical period” ending around puberty, after which second-language mastery showed a steady decline correlated with age.
However, more recent findings have added nuance to this age debate. A comprehensive 2022 study by Schepens, van Hout, and van der Slik evaluated over 50,000 adult immigrants to the Netherlands. It concluded that while aging is a significant obstacle to second language learning, the degree of difficulty is compounded by dissimilarities between one’s first language and the acquired target language.
These sources suggest childhood remains the optimal season for unadulterated second language acquisition. However, rather than an impenetrable “critical period,” adult learners face a more permeable continuum where age-related neuroplasticity interacts with factors like linguistic proximity in complex ways.
As demonstrated above, synthesizing sources involves:
- Extracting key ideas and conclusions from each source
- Identifying agreements, tensions, and intersections between sources
- Combining sources through critical analysis to develop an original, well-substantiated perspective
How to synthesize sources
Begin by grouping your sources thematically around common topics, theoretical frameworks, methodologies, or debate points they engage with. As you review each source, identify:
- The core research questions, hypotheses, or aims
- Key findings, arguments, or perspectives
- Confluences or divergences from other works in their evidence or conclusions
Once you have distilled the essence of each source, look across them for connections. Where do they substantiate each other’s claims? Where do positions markedly differ, directly contradicting or offering an alternative view?
Construct your synthesis by framing these sources in dialogue, elucidating explicit areas of agreement/disagreement and more nuanced tensions or synergies. Use source attributions, transitions, and your own voice to guide the reader through this analytical interplay:
- “Building on X’s groundbreaking study which demonstrated Y, later research by Z uncovered complementary evidence that…”
- “However, findings from A and B offer a counterpoint to this model, instead suggesting…”
- “Reconciling these somewhat disparate perspectives points to an emerging synthesis where…”
Do not simply accept stated disagreements between sources at face value. Interrogate more deeply – authors may clash due to differing theoretical lenses, methodological approaches creating constrained insights, or limited data sets from their respective contexts. Your synthesis should delineate these underlying reasons for (dis)agreement.
Additionally, look for implicit tensions that authors themselves may not directly acknowledge. For example, an innovative technology one source studies may undermine assumptions in another’s policy recommendations.
Your synthesis aims to comprehensively map out areas of consensus and conflict among your sources, combining their individual viewpoints into a more unified, nuanced understanding informed by your own reasoned analysis and critique.
Synthesis matrix
Visually mapping out relationships between multiple sources can help clarify areas of agreement, disagreement, and dialogue. A synthesis matrix provides a useful template for this process.
A synthesis matrix is a grid or table where each column represents one source, and each row captures a core topic, method, finding, or other themes addressed across sources. Populating the relevant cells concisely summarizes how each source approaches that particular idea.
For example, here is a synthesis matrix examining sources exploring factors impacting second language acquisition:
| Theme | Lenneberg (1967) | Johnson and Newport (1988) | Schepens, van Hout, and van der Slik (2022) |
| Approach | Mainly theoretical, focusing on the ethical ramifications of delaying language exposure | Administered English grammar proficiency tests on 46 native Korean or Chinese speakers who relocated to the US between ages 3 and 39, all residing in the US for at least 3 years | Analyzed data from 56,024 adult immigrants to the Netherlands from 50 language backgrounds |
| Enabling factors in language acquisition | Highlights a crucial period from infancy to puberty, suggesting a decline in language acquisition after that | Identifies a pivotal period similar to Lenneberg’s concept | Explores general age-related effects and the impact of a learner’s first language on acquiring a target language |
| Barriers to language acquisition | Emphasizes aging as a significant hindrance | Also acknowledges aging as an obstacle, aligning with Lenneberg’s perspective | Considers aging and the influence of disparities between a learner’s first language and the target language |
Viewing sources through this matrix layout instantly surfaces areas of convergence and divergence. The first two sources validate Lenneberg’s “critical period” hypothesis, while the third complicates it by introducing linguistic dissimilarity as another key variable.