Question 1

Dr. Schreiber is performing a within-subjects visual search experiment, which is a little like a video game. People seem to get a good deal better at the task after about 10 practice trials. What should be a concern for his experimental design?

Accepted Answer

Order effects are a concern in within-subjects designs because participants may become better or worse at the task simply because of the order in which they complete the trials. In this case, the improvement after 10 practice trials may be due to order effects rather than actual learning. To address this concern, Dr. Schreiber could counterbalance the order of presentation for the visual search task across participants.

Question 2

A well-designed experiment will

Accepted Answer

A well-designed experiment should adequately control for threats to validity, which refer to factors that could affect the accuracy of the results. While it is important for an experiment to be reliable (consistent in producing the same results), ruling out all possible threats to reliability may not be feasible or necessary. Additionally, the goal of an experiment is not necessarily to confirm the hypothesis, but to test it and gather empirical evidence to support or refute it.

Question 3

The conditions of a true experiment allow a researcher to infer

Accepted Answer

The key characteristic of a true experiment is the ability to establish causality, meaning that changes in the independent variable are directly responsible for changes in the dependent variable. This is achieved through the manipulation of the independent variable in a controlled setting, allowing for the possibility of causal inference. While reliability and validity are important aspects of any research study, they can be achieved through other means besides a true experiment. Manipulation is a crucial aspect of a true experiment but it is not sufficient on its own to establish causality.

Question 4

The two basic elements of a true experimental design are

Accepted Answer

A true experimental design requires both a control group or condition to compare against the experimental condition, and random allocation of subjects to different groups to ensure that the groups are comparable and that the results are not due to pre-existing differences between participants.

Question 5

An experiment always has at least

Accepted Answer

An experiment must have at least one independent variable, which is the variable that is manipulated or changed by the researcher. The other options are not necessarily required for an experiment.

Question 6

Random allocation of subjects to groups

Accepted Answer

Random allocation of subjects to groups helps to ensure that the groups will be equivalent before any experimental manipulation is introduced, thus reducing potential confounding variables and improving the internal validity of the study.

Question 7

Which one of the following procedures is an appropriate way to control for order effects in a within-subjects experiment? Arrange so that each condition

Accepted Answer

Controlling for order effects in a within-subjects experiment requires counterbalancing, which means presenting the conditions in different orders to different participants. Option B, occurring equally often in each ordinal position, helps ensure that each condition occurs an equal number of times in each possible position in the order of presentation. This can help minimize order effects and reduce bias. The other options do not achieve counterbalancing and therefore do not control for order effects adequately.

Question 8

Dr. Pritts is trying to determine whether elevated levels of a particular hormone alter rats' spatial ability. She injects rats either with the hormone or a saline solution, then times how long it takes them to find the hidden platform in a Morris Water Maze. In this problem,

Accepted Answer

The answer of Dr. Pritts is trying to determine whether...

Question 9

An independent variable is also referred to as a

Accepted Answer

While levels, conditions, and treatments can all be components of an experiment, an independent variable specifically refers to the factor being manipulated or controlled by the researcher. This factor is independent of other variables in the study, meaning that it can be changed or varied without affecting other variables in the experiment. Therefore, the correct answer is C, factor.

Question 10

Participants in a within-subjects experiment are performing an odor identification task in which the smell of vinegar is presented at a particularly high concentration. The smell that follows the presentation of the vinegar is always poorly identified, regardless of which odorant it is. What should be a concern for this experimental design?

Accepted Answer

This is most likely a sequence effect, where the presentation of vinegar is influencing the identification of the subsequent smells. A within-subjects design means that all participants experience the same sequence of odor presentations, so any effect that carries over from one trial to the next could be considered a sequence effect. Order effects refer to the influence of the order in which conditions are presented (e.g., experiencing one condition before another) and are not as likely to be a concern in this specific scenario. Random allocation to groups and mortality are not relevant to this experiment design.

Question 11

Which one of the following variables is most experimentally manipulable?

Accepted Answer

Teaching method is the most experimentally manipulable variable among the given options because it can be controlled and manipulated by the researcher in a controlled experiment. The other variables, such as athletic ability, student ability, and socioeconomic level, are not easily manipulable and are often outside the researcher's control.

Question 12

In a well-designed experiment, selection bias is controlled by

Accepted Answer

Random allocation of subjects to conditions helps to control for selection bias by ensuring that each participant has an equal chance of being assigned to any of the conditions being tested. This reduces the likelihood that any pre-existing differences in the characteristics of the participants will affect the results of the experiment. The existence of a control condition, the use of an independent variable, and a within-subjects design can all help to control for other types of bias in an experiment, but they are not specifically targeted at selection bias.

Question 13

A __________ is a particular value of an independent variable.

Accepted Answer

A level refers to a particular value or category of an independent variable in a study. For example, if the independent variable is "type of therapy," the levels may be cognitive-behavioral therapy, psychodynamic therapy, and mindfulness-based therapy. Levels are important in experimental design because they represent the different conditions that participants are exposed to, which allows researchers to draw conclusions about cause-and-effect relationships.

Question 14

The way in which subjects are treated in an experiment is referred to as the

Accepted Answer

Both options B (condition) and C (treatment) are correct. Subjects are assigned to different conditions or treatments in an experiment to observe the effects of the independent variable on the dependent variable. Therefore, the terms condition and treatment can be used interchangeably in this context. Option A (factor) refers to the independent variable itself, rather than the way in which subjects are treated.

Question 15

Which one of the following procedures is an appropriate way to control for sequence effects in a within-subjects experiment? Arrange so that each condition

Accepted Answer

Counterbalancing is a method used to control for sequence effects by ensuring that each condition follows every other condition an equal number of times.

Question 16

An independent variable always has at least two

Accepted Answer

An independent variable is a variable that can be manipulated or controlled by the researcher. It is designed so that it has at least two levels or variations to determine the effect on the dependent variable. For example, if the independent variable is "amount of caffeine," it may have two levels such as "no caffeine" and "high caffeine." Therefore, the best choice is A) levels.

Question 17

A research procedure in which the scientist has complete control over all aspects of the study is called:

Accepted Answer

A true experiment is the one in which the researcher has complete control over all aspects of the study. This includes the selection of participants, manipulation of the independent variable, and measurement of the dependent variable. In a true experiment, the researcher can randomize participants to different conditions, which increases the internal validity of the study.

Question 18

Professor Johns is performing an experiment to test hypnosis as a treatment for smoking. He is trying to decide which type of experimental design will be appropriate for the study. Which would you suggest?

Accepted Answer

A between-subjects design is appropriate for this study to avoid carryover effects, which could occur if the same subjects were exposed to both the treatment and control conditions (as in a within-subjects design). Carryover effects could confound the results, making it difficult to determine if changes in smoking behavior were due to the hypnosis or to the residual effects of being in both conditions.

Question 19

Order effects result from

Accepted Answer

The answer of Order effects result from
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Question 20

In a well-designed between-subjects experiment, the participants would

Accepted Answer

Random allocation to conditions ensures that participants have an equal chance of being assigned to any condition, which helps to control for individual differences and potential confounding variables. Assigning participants based on gender, or any other pre-existing characteristic or factor, could lead to biased results. Having participants experience each condition at least once would be a within-subjects design, and taking a pre-test prior to allocation to groups could potentially bias the results or limit the generalizability of findings.

Quiz 10: True Experiments, Part 1 Single-Factor Designs