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PubMed - an Introduction

An introduction to and guide for using PubMed - from basic research queries to in depth, personalized information discovery.

Automatic Term Mapping

When you conduct a search in PubMed, Automatic Term Mapping (ATM) may be applied to optimize your results, modifying or expanding your initial search terms. 

  • ATM works by matching search terms with associated MeSH terms, alternate spellings, and synonyms. It will also expand terms to include singular or plural versions. This can help to automatically make searches more sensitive. 
  • Sometimes ATM will expand searches in unwelcome ways by including irrelevant terms, and may also affect the reproducibility of searches. To disable ATM and improve precision in your search strategy, you can apply field tags to your search terms.  

a screenshot from PubMed search history displaying results and interpretation for searches with and without field tags applied. The search with field tag applied displays fewer results.