Playing three-dimensional video games can improve cognitive function in older adults. In a recent experiment (West et al., 2017), a sample of n = 15 older adults were instructed to play Super Mario 64 and similar 3-D games for six months. Participants’ scores on a cognitive assessment improved after the six-month treatment, relative to their scores on the cognitive assessment administered prior to the treatment. The authors observed a mean difference score of MD = 1.40, with a standard deviation of the difference scores of s = 2.59. a. Test the hypothesis that the treatment significantly affected cognitive performance. Use a one-tailed test with a = .05. b. Compute r2 as a measurement of effect size. c. Write a sentence demonstrating how the results of the hypothesis test and the effect size would appear in a research report.
> A developmental psychologist would like to determine whether infants display any color preferences. A stimulus consisting of four color patches (red, green, blue, and yellow) is projected onto the ceiling above a crib. Infants are placed in the crib, one
> The student population at the state college consists of 30% freshmen, 25% sophomores, 25% juniors, and 20% seniors. The college theater department recently staged a production of a modern musical. A researcher recorded the class status of each student en
> A recent study indicates that people tend to select video game avatars with characteristics similar to those of their creators (Bélisle & Bodur, 2010). Participants who had created avatars for a virtual community game completed a questio
> Many parents allow their underage children to drink alcohol in limited situations when an adult is present to supervise. The idea is that teens will learn responsible drinking habits if they first experience alcohol in a controlled environment. Other par
> Captive animals in laboratories or zoos benefit from environmental enrichment. In a recent experiment on the effects of enrichment on animal behavior, Robbins and Margulis (2014) compared the effects of different types of auditory enrichment on captive g
> The Internet is rapidly becoming an essential source of information about health, nutrition, finances, and current events. Neunschwander, Abbott, and Mobley (2012) were interested in inequality of access to the Internet as a function of the characteristi
> A sample of n = 9 scores has ΣX = 108. What is the sample mean?
> In a classic study, Loftus and Palmer (1974) investigated the relationship between memory for eyewitnesses and the questions they are asked. In the study, participants watched a film of an automobile accident and then were questioned about the accident.
> Parametric tests (such as t or ANOVA) differ from nonparametric tests (such as chi-square) primarily in terms of the assumptions they require and the data they use. Explain these differences.
> For the following scores, a. Sketch a scatter plot showing the six data points. b. Just looking at the scatter plot, estimate the value of the Pearson correlation. c. Compute the Pearson correlation.
> The following set of X values is the same as those used in Problem 23. For the following set of data: a. Compute the Pearson correlation statistic and compare your answer to the answer that you found for Problem 23. b. Find the linear regression equation
> The following results are from an independent-measures, two-factor study with n 5 10 participants in each treatment condition. a. Use a two-factor ANOVA with a = .05 to evaluate the main effects and the interaction. b. Compute h2 to measure the effect si
> A researcher conducts an independent-measures, two-factor study with two levels of factor A and two levels of factor B, using a sample of n 5 8 participants in each treatment condition. a. What are the df values for the F-ratio evaluating the main effect
> The following matrix presents the results from an independent-measures, two-factor study with a sample of n = 10 participants in each treatment condition. Note that one treatment mean (“M = ?”) is missing. a. What valu
> For the data in the following matrix: a. Which two means are compared to describe the treatment main effect? b. Which two means are compared to describe the main effect of age? c. Is there an interaction between age and treatment? Explain your answer.
> Suppose that a researcher conducts an independent samples experiment comparing three treatments. Participants serve in the experiment either online or by visiting the researcher’s lab. Scores for this hypothetical experiment are listed
> The following results are from an independent-measures, two-factor study with n = 4 participants in each treatment condition. a. Use a two-factor ANOVA with a = .05 to evaluate the main effects and the interaction. b. Test the simple effect of factor A a
> Find each of the following values for the distribution shown in the following polygon. a. n b. ΣX c. ΣX2
> Explain what happens during each of the two stages of the two-factor ANOVA.
> The following results are from an independent-measures, two-factor study with n = 5 participants in each treatment condition. a. Use a two-factor ANOVA with a = .05 to evaluate the main effects and the interaction. b. Test the simple effect of factor A a
> In a classic study of the effect of memory on caffeine, Loke (1988) studied the effect of caffeine on the serial position effect. In memory tests, the serial position effect refers to the observation that memory for items at the beginning and end of a li
> You might have heard the claim that students have specific “learning styles” and that each student learns best when the method of instruction matches their specific learning style. This claim has not held up to experim
> Emoticons, like and , are helpful for expressing emotion in communications that otherwise have limited emotional content (e.g., emails, text messages, and social media posts). Derks, Bos, and von Grumbkow (2007) conducted an independent sample experiment
> Most sports injuries are immediate and obvious, like a broken leg. However, some can be more subtle, like the neurological damage that may occur when soccer players repeatedly head a soccer ball. To examine effects of repeated heading, McAllister et al.
> Define each of the following terms: a. Factor b. Level c. Two-factor study
> Describe the similarities between an F-ratio and a t statistic.
> The following scores are from an independent-measures study comparing two treatment conditions. a. Use an independent-measures t test with a = .05 to determine whether there is a significant mean difference between the two treatments. b. Use an ANOVA wit
> To create the following data we started with the same sample means and variances that appeared in problem 29, but doubled the sample size to n = 10. a. Predict how the increase in sample size should affect the F-ratio for these data compared to the value
> For the following set of scores: a. Construct a stem and leaf plot. b. What is the shape of the distribution?
> The following data summarize the results from an independent-measures study comparing three treatment conditions. a. Use an ANOVA with a = .05 to determine whether there are any significant differences among the three treatment means. Note: Because the s
> For the preceding problem you should find that there are significant differences among the three treatments. One reason for the significance is that the sample variances are relatively small. To create the following data, we kept the same sample means th
> The following data were obtained from an independent- measures research study comparing three treatment conditions. Use an ANOVA with a = .05 to determine whether there are any significant mean differences among the treatments.
> Many know the feeling of being too groggy to take an 8 a.m. exam—we need to be more alert and aroused to do our best. Some of us also know the feeling of being too aroused by the prospect of an exam to do our best. Thus, the best level
> Why should you use ANOVA instead of several t tests to evaluate mean differences when an experiment consists of three or more treatment conditions?
> When you get a surprisingly low price on a product do you assume that you got a really good deal or that you bought a low-quality product? Research indicates that you are more likely to associate low price and low quality if someone else makes the purcha
> The following data are from a repeated-measures study examining the effect of a treatment by measuring a group of n = 9 participants before and after they receive the treatment. a. Calculate the difference scores and MD. b. Compute SS, sample variance, a
> The following data are from a repeated-measures study examining the effect of a treatment by measuring a group of n = 11 participants before and after they receive the treatment. a. Calculate the difference scores and MD. b. Compute SS, sample variance,
> How does the numerator of the repeated-measures t-statistic compare to the numerator of the single sample t-statistic?
> A repeated-measures and an independent-measures study both produce a t statistic with df = 15. How many subjects participated in each experiment?
> For the following set of scores: a. Construct a frequency distribution table. b. Sketch a histogram showing the distribution. c. What is the shape of the distribution?
> If you are using coffee to compensate for sleep loss, you might want to consider drinking your coffee under blue light. Beaven and Ekstrom (2013) recruited n 5 21 participants who completed a series of cognitive alertness and reaction time tasks under co
> Traumatic brain injury (TBI) is a significant health problem. TBI is caused by impacts to the head that might occur during contact sports, motor vehicle accidents, and similar events. TBI is known to produce cognitive impairments and reductions in brain
> A repeated-measures, a matched-subjects, and an independent-measures study all produce a t statistic with df = 10. How many participants were used in each study?
> A researcher conducts an experiment comparing two treatment conditions with 20 scores in each condition. a. If an independent-measures design is used, how many participants are needed for the study? b. If a repeated-measures design is used, how many part
> Explain the difference between a matched-subjects design and a repeated-measures design.
> To construct the following data, we started with the scores in Problem 20 and scrambled the scores in Treatment 2 to eliminate the consistency of the individual differences. a. If the data were from an independent-measures study using two separate sample
> Gamification refers to the application of game design and development to social, industrial, and educational settings. For example, a gamification program might award points or achievements to people for reaching specific goals. A recent experiment on ga
> Exercise is known to produce positive psychological effects. Interestingly, not all exercise is equally effective. It turns out that exercising in a natural environment (e.g., jogging in the woods) produces better psychological outcomes than exercising i
> Problem 17 demonstrates that removing individual differences can substantially reduce variance and lower the standard error. However, this benefit only occurs if the individual differences are consistent across treatment conditions. In Problem 17, for ex
> Place the following scores in a frequency distribution table. Based on the frequencies, what is the shape of the distribution?
> Swearing is a common, almost reflexive, response to pain. Whether you knock your shin into the edge of a coffee table or smash your thumb with a hammer, most of us respond with a streak of obscenities. One question, however, is whether swearing has any e
> Participants enter a research study with unique characteristics that produce different scores from one person to another. For an independent-measures study, these individual differences can cause problems. Identify the problems and briefly explain how th
> A sample of difference scores from a repeated-measures experiment has a mean of MD = 4 with a standard deviation of s = 6. a. If n = 9, is this sample sufficient to reject the null hypothesis using a two-tailed test with a = .05? b. Would you reject H0 i
> a. A repeated-measures study with a sample of n = 8 participants produces a mean difference of MD = 3 with a variance of s2 = 72. Use a two tailed hypothesis test with a = .05 to determine whether it is likely that this sample came from a population with
> a. A repeated-measures study with a sample of n = 6 participants produces a mean difference of MD = 4 with SS= 30. Use a two-tailed hypothesis test with a = .05 to determine whether this sample provides evidence of a significant treatment effect. b. Now
> There is some evidence suggesting that you are likely to improve your test score if you rethink and change answers on a multiple-choice exam (Johnston, 1975). To examine this phenomenon, a teacher gave the same final exam to two sections of a psychology
> Callahan (2009) demonstrated that Tai Chi can significantly reduce symptoms for individuals with arthritis. Participants were 18 years old or older with doctor-diagnosed arthritis. Self-reports of pain and stiffness were measured at the beginning of an e
> The stimulant Ritalin has been shown to increase attention span and improve academic performance in children with ADHD (Evans et al., 2001). To demonstrate the effectiveness of the drug, a researcher selects a sample of n = 20 children diagnosed with the
> A long history of psychology research has demonstrated that memory is usually improved by studying material on multiple occasions rather than one time only. This effect is commonly known as distributed practice, or spacing effects. In a recent paper exam
> Does posting calorie content for menu items affect people’s choices in fast-food restaurants? According to results obtained by Elbel, Gyamfi, and Kersh (2011), the answer is no. The researchers monitored the calorie content of food purchases for children
> Draw a polygon for the distribution of scores shown in the following table.
> Research results suggest a relationship between the TV viewing habits of 5-year-old children and their future performance in high school. For example, Anderson, Huston, Wright, and Collins (1998) report that high school students who regularly watched Ses
> Two separate samples receive different treatments. After treatment, the first sample has n = 5 with SS = 60, and the second has n = 9 with SS = 84. a. Compute the pooled variance for the two samples. b. Calculate the estimated standard error for the samp
> One sample has SS = 80 and a second sample has SS = 48. a. If n = 17 for both samples, find each of the sample variances, and calculate the pooled variance. Because the samples are the same size, you should find that the pooled variance is exactly halfwa
> In 1974, Loftus and Palmer conducted a classic study demonstrating how the language used to ask a question can influence eyewitness memory. In the study, college students watched a film of an automobile accident and then were asked questions about what t
> If other factors are held constant, explain how each of the following influences the value of the independent measures t statistic, the likelihood of rejecting the null hypothesis, and the magnitude of measures of effect size: a. Increasing the number of
> In a recent study, Piff, Kraus, Côté, Cheng, and Keltner (2010) found that people from lower socioeconomic classes tend to display greater prosocial behavior than their higher-class counterparts. In one part of the study, participants played a game with
> A researcher conducts an independent-measures study comparing two treatments and reports the t statistic as t(20) = 2.09. a. How many individuals participated in the entire study? b. Using a two-tailed test with a = .05, is there a significant difference
> In a classic study in the area of problem solving, Katona (1940) compared the effectiveness of two methods of instruction. One group of participants was shown the exact, step-by-step procedure for solving a problem and was required to memorize the soluti
> What causes us to overeat? One surprising factor might be the material of the plate on which our food is served. Williamson, Block, and Keller (2016) gave n = 68 participants two donuts each and measured the amount of food that was wasted by each partici
> Binge-watching a television show might not be the best way to enjoy a television series (Horvath, Horton, Lodge, & Hattie, 2017). Participants in an experiment watched an entire television series in the laboratory during either daily one-hour session
> What information is available about the scores in a regular frequency distribution table that you cannot obtain for the scores in a grouped table?
> Positive events are great, but recent research suggests that unexpected positive outcomes (e.g., an unseasonably sunny day) predict greater-than-normal amounts of risk-taking and gambling (Otto, Fleming, & Glimcher, 2016). Researchers demonstrated th
> Anxiety affects our ability to make decisions. Remmers and Zander (2018) demonstrated that anxiety also prevents us from intuiting about our environments. In their experiment, 111 participants were randomly assigned to receive either an anxiety-inducing
> Recent research has shown that creative people are more likely to cheat than their less-creative counterparts (Gino & Ariely, 2012). Participants in the study first completed creativity assessment questionnaires and then returned to the lab several d
> Find the t value that forms the boundary of the critical region in the right-hand tail for a two-tailed test with α = .05 for each of the following sample sizes. a. n = 9 b. n = 16 c. n = 36 d. Repeat parts a–c assuming a one-tailed test, α = .05. e. Rep
> The following sample of n = 5 scores was obtained from a population with unknown parameters. Scores: 20, 25, 30, 20, 30 a. Compute the sample mean and variance. (Note: These are descriptive values that summarize the sample data.) b. Compute the estimated
> The Muller-Lyer illusion is shown in the figure. Although the two horizontal lines are the same length, the line on the left appears to be much longer. To examine the strength of this illusion, Gillam and Chambers (1985) recruited 10 participants who rep
> In a classic study of procrastination by Lay (1986), in an introductory psychology class, students received a survey that measured procrastination. Participants were instructed to complete the survey and return it to the researcher by mail. High-procrast
> Oishi and Schimmack (2010) report that people who move from home to home frequently as children tend to have lower than average levels of well-being as adults. To further examine this relationship, a psychologist obtains a sample of n = 12 young adults w
> Your subjective experience of time is not fixed. You experience time “flying” during some activities and “dragging” during others. Researchers have shown that your experience of time can be altered by drugs that interact with the brain regions that are r
> To evaluate the effect of a treatment, a sample of n = 8 is obtained from a population with a mean of μ = 50, and the treatment is administered to the individuals in the sample. After treatment, the sample mean is found to be M = 55. a. Assuming that the
> For the following set of scores, find the value of each expression:
> To evaluate the effect of a treatment, a sample is obtained from a population with a mean of μ = 20, and the treatment is administered to the individuals in the sample. After treatment, the sample mean is found to be M = 22 with a variance of s2 = 9. a.
> People are poor at making judgments about probability. One source of error in judgments of probability is the base rate fallacy in which people ignore the base rates of low probability events. In a study of the base rate fallacy by Bar-Hillel (1980), par
> Weinstein, McDermott, and Roediger (2010) report that students who were given questions to be answered while studying new material had better scores when tested on the material compared to students who were simply given an opportunity to reread the mater
> To evaluate the effect of a treatment, a sample of n = 6 is obtained from a population with a mean of μ = 80, and the treatment is administered to the individuals in the sample. After treatment, the sample mean is found to be M = 72. a. If the sample var
> To evaluate the effect of a treatment, a sample is obtained from a population with a mean of μ = 40, and the treatment is administered to the individuals in the sample. After treatment, the sample mean is found to be M = 44.5 with a variance of s2 = 36.
> A random sample of n = 4 individuals is selected from a population with μ = 35, and a treatment is administered to each individual in the sample. After treatment, the sample mean is found to be M = 40.1 with SS = 48. a. How much difference is there betwe
> A random sample of n = 7 individuals is selected from a population with μ = 50, and a treatment is administered to each individual in the sample. After treatment, the following scores are observed: 37 49 47 47 47 43 45 a. Compute the sample mean an
> A random sample of n 5 9 individuals is selected from a population with m 5 20, and a treatment is administered to each individual in the sample. After treatment, the following scores are observed: 43 15 37 17 29 21 25 29 27 a. Compute the sample
> The National Study of Student Engagement (Indiana University, 2018) reports that the average, full-time college senior in the United States spends only μ = 15, s 5 9, hours per week preparing for classes by reading, doing homework, studying, etc. A state
> According to the CDC (2016), the average life expectancy of someone with diabetes is μ = 72 years, s = 14. Suppose that a sample of n = 64 people diagnosed with diabetes who received a blood glucose monitoring implant had an average life expectancy of M
> For the following set of scores, find the value of each expression:
> Define a Type I error and a Type II error and explain the consequences of each. Which type of error is worse? Why?
> Suppose that a researcher is interested in the effect of an exercise program on body weight among men. The researcher expects a treatment effect of 3 pounds after 15 weeks of exercise in the exercise program. In the population, the mean adult body weight
> Research has shown that IQ scores have been increasing for years (Flynn, 1984, 1999). The phenomenon is called the Flynn effect and the data indicate that the increase appears to average about 7 points per decade. To examine this effect, a researcher obt
> Telles, Singh, and Balkrishna (2012) reported that yoga training improves finger dexterity. Suppose that a researcher conducts an experiment evaluating the effect of yoga on standardized O’Conner finger dexterity test scores. A sample of n = 4 participan
> A researcher is evaluating the influence of a treatment using a sample selected from a normally distributed population with a mean of μ = 50 and a standard deviation of s = 10. The researcher expects a 15-point treatment effect and plans to use a two-tai
> After examining over one million online restaurant reviews and the associated weather conditions, Bakhshi, Kanuparthy, and Gilbert (2014) reported significantly higher ratings during moderate weather compared to very hot or very cold conditions. To verif
