Sometimes, when an eyewitness is brought in to make an identification of a perpetrator, the administrator of the lineup provides the eyewitness with positive feedback after they identify a suspect instead of a filler (e.g., great job!). A study was conducted to see if this feedback changed an eyewitness' confidence in their identification, as eyewitnesses often later have to appear in court to testify. Participants watched a mock video of a crime that manipulated the distance of the eyewitness from the perpetrator, such that they were either close or far from the perpetrator (operationally defined as 10 feet or 100 feet away, respectively). The eyewitness provided their confidence before and after receiving feedback on a 10-item Likert scale (1 = not at all confident, 10 = extremely confident). Demographic information (i.e., age and gender) was also collected. Make sure to familiarize yourself with how the data is coded. For example, the variable "Distance" is coded such that 0 = close to perpetrator and 1 = far from perpetrator.

Perform and interpret a t-test using SPSS (7 points)

Perform a two-tailed ttest with = .05 to answer the following question:

Is confidence before receiving feedback (pre_confidence) significantly different from confidence after receiving feedback (post_confidence)?

Q1. What type of ttest should be performed to answer this question? What is your rationale?(2)

Q2. What is your null hypothesis (non-directional)?(1)

Perform and Interpret a tTest using SPSS (7 points)

This eyewitness researcher manipulated the distance (variable "Distance") from the perpetrator, such that the perpetrator was close or far away in the mock crime video (coded as close = 0, far = 1). Run a two-tailed ttest with = .05 to answer the following research question:

Is there is a significant difference in pre-feedback confidence ratings (pre_confidence) for people who were close to or far from the perpetrator (distance)?

Q7. What type of ttest should be performed to answer this question? What is your rationale?(2)

Q8. What is your null hypothesis, written in symbols?(1)

Hint: The hypotheses should be non-directional this two-tailed test.