Question

A perceptual psychologist speculated that people can identify letters faster if they are surrounded by other letters in real words compared to letters in meaningless combinations.   For example, people should recognize the letter c in the word doctor faster than c in the letter stringtocdor.   He created a letter identification task where the stimuli were identical except in one condition the target letter was embedded in a word and in a second condition the letter was embedded in scrambled letters.   He created 200 stimuli, half of which were word trials and half were scrambled trials.   Thirty subjects participated in the study.    He assigned the first 15 subjects to sign up for the study to the word condition and the second 15 to the scrambled condition.   Reaction time was measured for each trial.   He hypothesized that reaction times would be faster for the word condition.  He performed a two-tailed t-test on the average reaction times for each group at the ?=.05 level.  He found that the mean reaction time for the word condition was significantly faster than for the scrambled condition.

What type of research design was used?

What were the independent and dependent variables?

How were subjects assigned to levels of the independent variable?

Was there a possible confound in the study?

Assume that word vs. scrambled context has no effect on people’s ability to identify letters.  What type of error did the experimenter make?

Can you think of ways to improve the study?

Answer 1

Research design used here is experimental research .

Words scrambled and correct words are the independent variables and subjects are dependent variables.

Random basis were followed in case of subject selection , 50 percent were given for exact words and rest for scrambled words.

Here confound is the merits of the subjects which experimenter can,t control.

If this is the scenerio it is a logical errors that experimenter has failed to observe.

Here in this case merits are not measured and thus the results that there is no effect on the ability affects the results of the tests because it depends on the intelligency quotient. It does not mean that a person with less merits show performance in the test as equivalent as the subject with higher merits.