Sentences describing the subjects or materials used in a study require either the past or the present tense. Notice that the boys described in the preceding example were specific individuals selected to take part in the study. In other words, they were a sample selected by the experimenters to represent an entire population of high risk boys. When we describe the sample used in a study we commonly use the past tense.
However, when describing the general population from which the sample subjects were selected, the present tense is normally used.
Use of Tenses with Conventional and Specially Designed Materials
We have seen previously that verb tense can be determined by whether you are describing a general population or a sample selected from a population. We find a similar convention determining verb tenses when we describe other materials. If you use equipment in your study which is standard or conventional in your field and probably familiar to most other researchers, you should describe it using the present tense.
On the other hand, descriptions of specially designed materials with which other workers in your field may not be familiar are usually written in the past tense. Common devices that you modified in some special way for use in your study are also sometimes described in the past.
Using Active and Passive Voice in Describing Materials
Both active and passive voice verb constructions are used in describing experimental materials. Your decision to use active or passive voice depends partly on whether the verb is transitive or intransitive. Only transitive verbs can be used in the passive voice. (Your dictionary will tell you if a given verb is transitive or intransitive.) If the verb is transitive, follow these rules to determine which voice to use:
1. The passive voice is usually used when a human agent (the experimenter) is manipulating the materials.
2. The active voice is usually used when no human is directly responsible for manipulating the materials-that is, when the materials operate "by themselves."
In examples C and D, the use of the active voice indicates that the experimenters were not directly involved in the functioning of the equipment.
3. The passive voice may be used to describe an action involving a nonhuman agent, but a phrase must be included to indicate the agent.
Results
The language conventions we look at in the results section of the report will help you to choose the appropriate verb tense or modal auxiliary for each element of information. We also examine some special words and expressions you can use to report different types of findings.
