Introduction
The materials and methods section of a research paper is where you describe the experimental design and procedures used to collect and analyze data for your study. This section allows readers to evaluate the appropriateness of your methods and the reliability and validity of your results, and to replicate your study if desired. Writing an effective materials and methods section takes time and careful description of procedures. This article provides a sample materials and methods section and discusses key components to include.
Sample Materials and Methods Section
Participants
The study included 120 participants between the ages of 18 and 30 who were recruited through social media ads and flyers posted around a mid-sized university campus. Participants were asked to complete an online screening survey to determine eligibility. Inclusion criteria were age 18-30, no history of neurological or psychiatric disorders, and normal or corrected-to-normal vision and hearing. Exclusion criteria were any current substance use disorders or medical illnesses. The final sample included 78 female and 42 male participants. All participants provided informed consent and received $10 compensation for their time. The university’s Institutional Review Board approved all study procedures.
Materials and Measures
Stimuli consisted of 30 positive and 30 negative images selected from the International Affective Picture System (IAPS; Lang et al., 2008). The IAPS provides standard normed stimuli for experimental research on emotion and attention. Images were matched on arousal and valence ratings from previous IAPS standardization procedures.
Participants completed self-report measures on a desktop computer using Qualtrics survey software. Trait positive and negative affect were assessed using the Positive and Negative Affect Schedule (PANAS; Watson et al., 1988). The PANAS contains 10 positive emotion items and 10 negative emotion items rated on a 5-point scale from very slightly or not at all to extremely. Higher scores indicate greater trait affect.
State affect was assessed before and after image viewing using the Self-Assessment Manikin (SAM; Bradley & Lang, 1994). The SAM uses graphic figures to rate current valence (unpleasant-pleasant), arousal (calm-excited), and dominance (in control-controlled) on 9-point scales.
Procedure
After providing informed consent, participants completed a demographic questionnaire and the PANAS trait measure. They were then instructed that they would view a series of images on the computer screen, each for 6 seconds, followed by the SAM state affect measure. Image presentation was randomized for each participant. Participants were asked to simply view each image naturally without regulating their emotional responses.
After image viewing, participants again completed the SAM to assess post-stimulus state affect. They were then fully debriefed and compensated. The entire session lasted approximately 30 minutes. Stimulus presentation and data collection were programmed using E-Prime 3.0 software.
Data Analysis
Data were analyzed using SPSS statistical software version 27. descriptive statistics characterized the sample. To test for changes in state affect from pre- to post-image viewing, paired-samples t-tests compared pre- and post-SAM scores separately for valence, arousal, and dominance. Bivariate correlations evaluated associations between trait affect and state affect change scores. Statistical significance was set at p < .05.