**Participants**
We plan to recruit 400 participants for a set of studies conducted on a computer in a lab. Participants will be recruited using a laboratory participant pool which consists mainly of students of Czech universities, but is open to other people as well. The study will be conducted with groups of up to 17 participants, so the final sample size may differ slightly from the planned 400.
The set of studies includes an instructional manipulation check (Oppenheimer, Meyvis, & Davidenko, 2009) and three items in scales that instruct participants to pick a certain response. We will exclude from analysis participants who fail to answer correctly the instructional manipulation check or at least two of the items in the scales.
Oppenheimer, D. M., Meyvis, T., & Davidenko, N. (2009). Instructional manipulation checks: Detecting satisficing to increase statistical power. Journal of Experimental Social Psychology, 45(4), 867-872.
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**Design**
Participants will be given in total 22 questions asking for a numerical judgment. The numerical judgment will be done on one of 22 possible scales (kg, km/h, °C, …). The questions will be divided in eleven conditions and each condition will be given to each participant twice. The conditions will differ in questions or instructions given before the target question. In particular the eleven conditions are:
low - target
high - target
target
low - high - target
high - low - target
(low - high) - low - target
(high - low) - high - target
low - low x target - target
high - high x target - target
low x target - target
high x target - target
Where “target” denotes the numerical judgment of interest (e.g., “What is the weight of a donkey in kilograms?”). “low” and “high” denote a similar question asking about an object (an animal in this case) for which the answer is higher (an elephant) or lower (a fox). “low x target” denotes a comparison question asking whether the attribute in question is higher or lower for the “low object” or for the “target object” (e.g., “Does a fox weigh more or less than a donkey?”). “high x target” has a similar meaning, but relates to the “high object” instead of the “low object”. Finally, “(low - high)” and “(high - low)” denote an instruction to “Estimate how many kilograms does a fox and elephant weigh and imagine these estimates on a numerical scale.”; where only the order of the objects differ between the two conditions.
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**Procedure**
The study will be conducted as a part of a set of unrelated studies on computers in a lab. After reading instructions related to the present study, participants will go through 18 rounds of the task. During each round, they will answer a numerical judgment, which will be preceded by answering related questions depending on a condition of the given round (with the exception of the control condition, where only the target judgment will be given). Only after answering a question (or pressing a button indicating that the participant followed instructions of the task) will a subsequent related question be displayed on the same screen. Therefore, participants will be able to reply only to a single question at each time. After making the final numerical judgment, participants will confirm their response by pressing a button, which will lead them to the next round.
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**Materials overview**
The full materials (in Czech) are in the Materials node. The study will use 18 different scales and three objects for each scale (low, target, high), where a numerical judgment to the target object will be analyzed. The scales and their corresponding objects (in the order of low, target, high) are listed below:
weight (kg): fox, donkey, elephant
movement speed (km/h): turtle, pig, tiger
average annual temperature (°C): Oslo, Rome, Dubai
duration of a flight (h.): Prague - London, Prague - Tel Aviv, Prague - New York
altitude (metres above sea level): Amsterdam (Netherlands), Berlin (Germany), Lhasa (Tibet)
GDP (billions of CZK): Somalia, Canada, Germany
length (cm): table tennis paddle, tennis racquet, hockey stick
age (years): Jiří Ovčáček, Michal Horáček, Karel Schwarzenberg
average precipitation (mm per month): Prague in March, Prague in September, Prague in July
population (): Belgium, Poland, Brasil
distance (km): Prague - Munich, Prague - Brussel, Prague - Athens
area (km2): Austria, France, Canada
volume (m3): average car, subway carriage, airship
area (ha): soccer field, Prague zoo, Ostrava
speed (rpm): gramophone record, car wheels on a highway, PC hard drive
fuel consumption (l/100km): average car, fully loaded truck, Boeing 737
voltage (V): AA battery, electric chair, railway lines
calories (kcal): carrot, strudel piece, normal package of butter
annual deaths in the Czech Republic (people/year): drowning, car accident, heart failure
year of birth (year of common era): Otakar II. of Bohemia, George of Poděbrady, Maria Theresa
decibels (db): whispering, normal speech, shouting
unemployment (%): Germany, Italy, Greece
Example translated materials for one of the scales:
weight (kg)
*low*: What is the weight of a fox in kilograms?
*target*: What is the weight of a donkey in kilograms?
*high*: What is the weight of an elephant in kilograms?
*(low - high)*: Estimate how many kilograms does a fox and elephant weigh and imagine these estimates on a numerical scale.
*(high - low)*: Estimate how many kilograms does an elephant and a fox weigh and imagine these estimates on a numerical scale.
*low x target*: Does a fox weigh more or less than a donkey?
*high x target*: Does an elephant weigh more or less than a donkey?