91Ó°ÊÓ

In a 2017 study designed to investigate the effects of exercise on secondlanguage learning, 40 subjects were randomly assigned to one of two conditions: an experimental group that engaged in simultaneous physical activity while learning vocabulary in a second language and a control group that learned the vocabulary in a static learning environment. Researchers found that learning second-language vocabulary while engaged in physical activity led to higher performance than learning in a static environment. (Source: Liu et al., "It takes biking to learn: Physical activity improves learning a second language," PLoS \(O n e\), May 18,2017, https://doi.org \(/ 10.1371\) /journal. pone.0177624) a. What features of a well-designed controlled experiment does this study have? Which features are missing? b. Assuming that the study was properly conducted, can we conclude that the physical activity while learning caused the higher performance in learning second-language vocabulary? Explain.

Step by step solution

01

Identifying features of a well-designed controlled experiment

In this study, several features of a well-designed controlled experiment are present: i. Clearly defined variables, here being whether the subjects were engaged in physical activity while learning vocabulary or not. ii. Random assignment of subjects: The 40 subjects were randomly assigned to either the experimental group or the control group. iii. Control group for comparison: The control group is those subjects who learned the vocabulary in a static learning environment. iv. Objective measurement of results: The performance of learning second-language vocabulary is the result being measured.\nHowever, details about procedural consistency among subjects (i.e. all subjects undergoing the same conditions apart from the tested variable) and whether the researchers ensured this, are missing.

02

Determining causality

Assuming the study was properly conducted, stating that physical activity while learning caused the higher performance in learning second-language vocabulary is plausible. The experimental setup was designed such that the only variable differing between the control and experimental group was whether or not they were engaged in physical activity while learning, implying a causal link between physical activity and improved vocabulary learning. However, one should also consider possible confounding variables that may have not been controlled.

Unlock Step-by-Step Solutions & Ace Your Exams!

• Full Textbook Solutions

  Get detailed explanations and key concepts

• Unlimited Al creation

  Al flashcards, explanations, exams and more...

• Ads-free access

  To over 500 millions flashcards

• Money-back guarantee

  We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Random Assignment

Random assignment is a key component of a controlled experiment. In the study, the 40 subjects were randomly allocated to either the experimental group or the control group. This method ensures that each participant has an equal chance of being placed in any group, reducing potential biases.
This balance helps ensure that differences in outcomes are due to the experimental manipulation rather than pre-existing differences between groups.
By employing random assignment, researchers can more confidently attribute differences in learning outcomes to the effect of physical activity rather than other variables.

Control Group

In any controlled experiment, having a control group is crucial. The control group serves as a baseline against which the effects of the experimental intervention can be measured.
In this study, the control group was made up of subjects who learned the vocabulary in a static environment. Their performance is contrasted with the experimental group to determine the impact of the physical activity.
A well-defined control group allows researchers to better isolate the effect of the independent variable, which is the physical activity undertaken by the experimental group.

Experimental Design

Experimental design is about structuring the study to test a hypothesis under controlled conditions. A good experimental design includes several elements such as random assignment of participants and the inclusion of a control group.
The 2017 study investigated whether physical activity affects language learning by setting up two distinct conditions. The first group engaged in physical activity, while the second did not.
A robust experimental design aims to minimize the effects of confounding variables and ensure that consistent conditions are maintained, except for the variable being tested.

Causal Inference

Causal inference is determining whether the variable of interest truly causes an observed effect. In this study, the researchers wanted to know if physical activity improved vocabulary learning.
If the study was well-conducted, differences in vocabulary learning can likely be attributed to physical activity. However, causal inference also requires careful consideration of potential confounding factors, such as participants' prior motivation or different execution in the tasks.
Valid causal inference gives confidence that the outcomes are indeed a result of the controlled variable, helping to inform future educational strategies that incorporate physical exercise.