Stroop Effect 

1. Empirical Report Instructions

General Requirements

As described in the Course Information, you are required to participate in a cognitive experiment using the Experiments in Cognition software. The data you collect from yourself will be used to write an empirical research paper. Research papers are an important component of any educational experience, and will help you to develop and refine the following academic skills:

1. Critical reading of original research literature.
2. Summarizing and integrating research findings.
3. In-depth analysis and understanding of a topic of interest.
4. Objective writing for an academic audience.

The format of the paper must follow the Publication Manual of the American Psychological Association (6th ed.), or simply APA style. You are encouraged to complete the APA Style Tutorial, and review the sample empirical report. Completing the empirical research paper and writing the results in APA style will enable you to achieve the following specific goals:

1. Obtain an experiential component to understanding research on cognition.
2. Enhance your appreciation for the research techniques used to investigate a mental phenomenon.
3. Apply APA format in a research paper assignment.

Once completed, your empirical report should be submitted to the Empirical Research Paper Dropbox on the main course page. Please review Moodle Orientation for instructions on how to use the Dropbox.

Experiments

You may choose from any of the five experiments described in this manual. Some of these experiments are discussed in Matlin (2013), and are replications or variants of well-known cognitive tasks that are noted for producing robust and reliable effects. A description of each experiment is provided along with detailed participant instructions. Before starting any experiment, it is very important that you read the Participant Instructions thoroughly as they provide important details about the tasks required for the experiment and how to respond.

To complete an experiment, you will need a computer with Internet access to download the course software, Experiments in Cognition. General instructions on how to download and start the software are described in the next section.

Each experiment will begin with an electronic Informed Consent form. You will be presented with a summary of the task requirements, and will be asked to click on a button to indicate your consent to participate. Informed consent is a necessary ethical requirement when conducting any type of research with human participants. On this page, you will have the option to indicate: (a) full participation in order to complete the paper requirements; (b) limited participation in order to learn more about the experiment; or (c) exit. If you indicate full participation, your data will be uploaded to a secured server in partial fulfillment of the paper requirements. You are only required to complete one experiment under full participation but you are encouraged to participate in any of the other experiments any number of times by indicating limited participation. If you select this option, your data from the experiment will only be stored on your computer. You might find that this option provides you with a better understanding of the cognitive phenomenon under investigation.

Marking Outline

Your empirical research report in APA style will comprise the following sections.

1. Title Page (2 points):The title page should contain the following elements in the APA prescribed positions: Running Head, Page Number, Title, Author, and Afilliation. You do not need to include Author Notes.
2. Abstract (6 points):The abstract is a 120-word summary of the entire paper, and is typically written last. The abstract succinctly summarizes the crucial elements of the four major sections of the empirical report (Introduction, Method, Results, and Discussion).
3. Introduction (35 points):The introduction provides a brief but thorough review of the relevant literature that leads to the hypothesis and the predicted results. The description of each experiment in the assignment manual is also accompanied by two references: the original study upon which the experiment is based, and a review of the literature relevant to the experiment. You are required to seek out three additional references using the online databases that are available from the Athabasca University Library (PsycInfo, ProQuest, etc.). Use the review article to identify topics or issues that you feel are relevant when selecting the additional references. In total, your paper should be based on at least 5 sources.

The experiment descriptions also include a statement about dependent and independent variables. You will recall that experiments are defined by the presence of independent variables (variables manipulated by the experimenter) and the dependent variable (the variable measured by the experimenter). The general hypothesis of any proper experiment is that manipulations of the independent variable will cause changes in the dependent variable. Unlike other research methods, the experiment is capable of testing causal relations between variables. As you conclude the introduction, your review should naturally lead to a statement of the hypothesis and your predicted results. The predictions should be supported by the review.

4. Method (15 points):The method section is the objective summary and administration of the task, such that the experiment could be repeated by another researcher interested in replicating your findings. Be sure that your Method section contains the following subsections, as described in the APA Style Manual: Participants, Materials, and Procedure. Under Participants, you only need to describe the relevant characteristics of yourself as the lone participant. Those unfamiliar with APA format are strongly advised to consult the Style Manual before completing this section.
5. Results (7 points):The results section of an experiment usually involves the presentation of descriptive and inferential statistics. Descriptive statistics are summary statistics. Inferential statistics are tools used to determine whether the obtained findings are statistically significant. In this paper, you are only required to complete a descriptive analysis of your findings in the form of a table or figure (but not both). If you follow the instructions for the experiment, you will end up with a set of summary measures of your performance. This information will be used to construct an APA-style table or figure to include in your research paper. The table or figure will constitute the major portion of the results section.
6. Discussion (10 points):The discussion section provides an interpretation of the findings with respect to the predictions made in the Introduction. You can also include your own observations and impressions of the experience as a participant, any limitations or shortcomings, and/or any future directions.
7. References (5 points):The reference section contains a list of works actually read and cited in the body of the paper. All references must adhere to APA style.

Your research paper should be 10 to 12 double-spaced pages. In addition to the preceding components, your writing style (grammar and spelling) will be marked out of 10 points, and adherence to general APA format will be marked out of 10 points.

2.           Experiment 1: Stroop Effect

Experiment Description

The Stroop effect (Stroop, 1935) is a robust phenomenon with a long history of study in cognitive psychology. As described in Chapter 3 of the Matlin text, the Stroop effect refers to an attentional finding that reveals how difficult it can be to focus on one thing (or, alternatively, to ignore something else). In the classic demonstration of the Stroop effect, words that are names of colours are presented to the participant in coloured ink, and the participant is required to ignore the word and name the ink colour. When the ink and word are consistent (e.g., the word “red” is written in red ink), responses are generally quick. However, when the ink and word are inconsistent (e.g., the word “red” is written in green ink), responses are relatively slower.

In this experiment, you will be asked to indicate the colour of a computer-presented letter string by pressing a corresponding computer key as quickly as possible. There will be three conditions. In condition 1 (Neutral) the coloured letter strings will be composed of Xs. In condition 2 (Inconsistent) the letter strings will consist of colour words (e.g., red, green, blue) displayed in a colour different than the colour specified by the word. In condition 3 (Consistent) the letter string will consist of colour words displayed in the same colour specified by the word. You will test whether your reaction time in identifying the colour (i.e., the dependent variable) is affected in the consistent and inconsistent conditions when compared to the neutral condition (i.e., the independent variable).

The following sources are strongly recommended as review materials for completing your paper and are available online through the AU library. You are also required to seek out three additional references for a total of five sources.

Original Study: Stroop (1935). Studies of interference in serial verbal reactions. Journal of Experimental Psychology, 18, 643-662.

Review Article: MacLeod, C. M. (1991). Half a century of research on the Stroop effect: An integrative review. Psychological Bulletin, 109, 163-203.

Participant Instructions

On each trial in this experiment, a plus sign will appear briefly in the center of the screen for 500 milliseconds, and will be immediately followed by a string of letters printed in one of four colours. Your task is to respond to the COLOUR of the letter string by pressing the correct key as quickly as possible. The appropriate key to press for each colour is as follows:

red = z   green = x   blue = .   yellow = /

The computer key-colour assignments will be displayed at the top of the screen but you may also want to tape colour terms (or colour patches) to your computer keys to help you keep track of the colour-key assignments.

If the response is correct, the next trial will begin in 1500 milliseconds. If the response is not made within the 1500 milliseconds, or if the response is incorrect, or if an invalid key is pressed, a short tone will be presented and the next trial will begin in 1500 milliseconds.

Each of the three conditions will be presented twice in blocks of 36 trials (i.e., six blocks of 36 trials), and the order of conditions across blocks and the order of trials within a block will be determined randomly. You will have an opportunity to take a short break between blocks. In addition, there will be a set of 18 practice trials (6 trials for each condition) at the beginning of the experiment.

The raw data from the experiment (216 responses) can be examined by clicking the View Raw Data button.

To summarize these data, click on the Analyze Raw Data button to compute the mean and standard deviation of the reaction times for correct responses in each of the three conditions. This button will also calculate the number of valid trials for each condition or the number of trials where a correct response was provided. Outwardly, this button produces no observable effect but must be pressed for the next button to work.

To view the summarized results, click on the View Summarized Data button. This summary is important, and will be necessary to prepare an APA style table to include with your paper. Please note that, although the summary data appear in tabular form, the format is not in APA style. Part of your task is to create an APA table from the summarized data.

To view the results of previous participants, click on the Display Group Data button. This button will display the average reaction time for the three conditions. You can use this information to compare with your own performance. This button will not work until you have participated in the experiment.