PSC482G, Spring 2000
Answers to Assignment 2
Critical thinking 2

Read:
The essays “Types of evidence useful for understanding the JFK assassination” and “Shadings of eyewitness testimony.”

Answer these questions:
“Types of evidence”:
This assignment is designed to start you thinking about the properties of different types of evidence and their inherent degrees of usefulness. The table below lists ten examples of evidence from the JFK case, each of which is explained in more detail below the table. For each entry, fill in whether it is testimonial or demonstrative (T or D), direct or indirect (D or I), conclusive, persuasive, or weak (C, P, or W), testable or untestable (T or U), and right or wrong (R or W). Fill in the last column only if appropriate (if the evidence is testable) and if you already know the answer.

Examples of evidence
      1. “Earwitness” reports by nearly 100 persons in Dealey Plaza who heard shots fired from the grassy knoll.
      2. Bullet fragments recovered from the scene that were traced ballistically to only one rifle.
      3. The Mannlicher-Carcano rifle owned by Lee Harvey Oswald and allegedly fired by him.
      4. The X-rays of Kennedy’s head, taken during the autopsy, that show lead fragments coning outward from the small hole in the back to the large hole in the right front, as evidence for hit from rear.
      5. Howard Brennan’s report of seeing the final shot fired from the Texas School Book Depository, plus his description of the shooter.
      6. Julia Mercer’s report of seeing a man carrying a rifle to the grassy knoll an hour before the assassination, as evidence for a shooter on the knoll.
      7. The footprints found in the mud behind the picket fence on the grassy knoll by James L. Simmons, as evidence of shooter on the knoll.
      8. The Cuban exiles’ anger over the failed Bay of Pigs invasion as reason for them to kill Kennedy.
      9. Kennedy’s dual motions after the head shot, as shown by the Zapruder film, as evidence for direction of final shot.
      10. Reports by the three men on the fifth floor of the Depository, who heard a rifle being fired directly above them.

“Shadings of eyewitness testimony”:
Here are ten characteristics of Dealey Plaza during and after the assassination. Explain how each would have affected the ability of eyewitnesses to perceive and record the events and later describe them.

      1. The shots came unexpectedly. Will weaken the witnesses’ ability to perceive them properly.
      2. The shots came from a direction or directions that were difficult to determine because the plaza was ringed by tall buildings and other structures that created complex echoes. Will weaken the witnesses’ ability to associate the proper direction(s) with them.
      3. The crowd in the plaza must have thought that it was being fired upon. Fear for personal safety would have weakened the witnesses’ ability to perceive and remember details about the shots. They would first have tried to protect themselves.
      4. Panic ensued, and some witnesses dropped to the ground instinctively. Would also have disrupted their ability to perceive and remember properties of the shots.
      5. The whole thing was over in a matter of seconds and the motorcade sped away to Parkland Memorial Hospital. The shortness of the event would have made it harder to remember details. The motorcade’s speeding away would have distracted the witnesses’ attention in the critical first few moments when they could have been organizing their memories of the shots.
      6. The Dallas police immediately began searching the area and the nearby buildings. The confusion associated with the search, coming so soon after the shots, would also have worked to confuse their memories.
      7. The Dallas police began questioning people and taking statements within minutes. The questions soon after the event would have helped the witnesses organize their thoughts in the relatively early stages.
      8. People compared impressions and tried to determine what had just happened. Would have induced some witnesses to agree with the “group.”
      9. Everyone knew that their president, their governor, and/or their vice president had been fired upon. Would have added to the stress of the event and therefore would have made it harder to remember the events.
      10. The whole event was set against the backdrop of the height of the Cold War. Natural fears of this being the opening salvo of something potentially much larger would have increased the stress and made the events more difficult to remember properly.

Summary: 9 of 10 factors were unfavorable for witnesses’ remembering the events accurately. No wonder the actual accounts varied so much!

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