A neuroscientist wanted to investigate whether there was a correlation between salivary alpha-amylase levels (measured in U/mL) and mean reaction times (measured in milliseconds) on a rapid visual attention task under pressure.
An advertisement was uploaded to a local community center's public forum inviting healthy adults aged 20 to 35 to participate. Nine participants responded and were recruited for the study. Each participant completed the attention task and immediately provided a saliva sample to assess their alpha-amylase levels.
The results of the reaction time task and the salivary assays are displayed in Table 1.
| Participant | Salivary alpha-amylase level (U/mL) | Mean reaction time (ms) |
|---|---|---|
| A | 120 | 320 |
| B | 85 | 385 |
| C | 150 | 290 |
| D | 95 | 370 |
| E | 110 | 340 |
| F | 70 | 410 |
| G | 135 | 305 |
| H | 105 | 350 |
| I | 165 | 275 |
Name the sampling technique that was used in this investigation.
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