Parafoveal Priming

Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond

Created: January 10, 2012

Last Modified: January 10, 2025 by K. Borchert (katjab@millisecond.com), Millisecond

Script Copyright © Millisecond Software, LLC

Background

Scripts implements a Parafoveal Priming Procedure.This parafoveal priming task was used by Chartrand & Bargh (1996) to subliminally activate participants' impression formation mode.

In general, priming procedures are simple response-timed binary categorization tasks of items from two target categories (e.g. positive vs. negative adjectives). Priming Procedures are based on the assumption that people respond faster if the target category was already 'mentally activated' by briefly presenting items (called 'primes') that are closely connected in one's mind. Thus, a person should be faster to quickly categorize the target word 'good' as 'positive' after the brief presentation of the prime word 'ice-cream' than after the brief presentation of the prime word 'famine'. If the primes are presented with a temporal duration that can be consciously processed, the primes are called 'supraliminal'. If the the duration of the primes is so short that they are outside one's conscious awareness the primes are called 'subliminal'.

In this particular task, no actual target categories are used. The primes are presented either on the left or right side of the monitor at subliminal speed and covered by a 'mask' of random characters. The resulting visual 'flash' is to be categorized as being on the 'left' or 'right'. This procedure is used to simply activate the priming categories.

This script uses the original text stimuli but could easily be adapted to a new purpose. Please be aware that this script uses absolute stimulus sizing and thus depends on a minimum size monitor. If the current monitor is deemed too small to run the current script, the script prematurely terminates.

References

Chartrand, T.L & Bargh, J.L. (1996). Automatic Activation of Impression Formation and Memorization Goals: Nonconscious Goal Priming Reproduces Effects of Explicit Task Instructions. Journal of Personality and Social Psychology, 71, 464-478.

Duration

8 minutes

Description

Categorize brief "flashes" on the screen as left or right flashes by key press.

Procedure

(1) 6 Practice Trials (with error feedback)
(2) 75 trials for condition "priming"/"nopriming": randomized order of the 4 different text stimuli,
stimuli are selected at random with replacement
(3) 6 different Stimuli Onset Asynchronies (2000-7000ms); randomly selected with replacement
(4) 4 screen quadrants for the primes are selected randomly with replacement
(5) between participant design: half the participants get the prime words the other half the noprimes (see Chartrand & Bargh, 1996);
Assignment is done by "group number"
(6) Participants should have a monitor-eye distance of 99cm (see Chartrand & Bargh, 1996)

Stimuli

(1) Practice Stimuli: in this script, the practice trials use unrelated stimuli
(2) Priming/noPriming conditions: use the original 4 text stimuli from Chartrand & Bargh (1996).
(3) Fixation Stimuli: 3 "+++ " in the middle of the screen
(4) Specifics for Stimuli Location/Size:
(a) Most experimental stimuli sizes and screen positions in this script are absolute and NOT percentages of the monitor size
and thus depends on a minimum sized monitor.
If the current monitor is deemed too small to run the current script, the script prematurely terminates.
The appropriate sizes are automatically calculated for the current monitor size.
(b) the prime's center is 7.6cm away from the fixation symbols on the 45degree angle (135, 225, 315) (see Chartrand & Bargh, 1996).
=> the middle of the prime is at 4degree visual angle (if participants sit 99cm away from screen)
=> the boundary conditions for the size of the prime are 2degree-6degree visual angle (see Chartrand & Bargh, 1996)
(c) Location of Primes: the location of primes in one of the four screen quadrants is randomly determined (Chartrand & Bargh, 1996,
used one predetermined sequence)
(d) Timing of Primes: the intervals between stimuli presentation is randomly determined (Chartrand & Bargh, 1996,
used one predetermined sequence)
Participants can respond to the "flashes" at any time during that interval, but are instructed to respond as fast and accurately as possible.
Stimulus Onset Asynchrony (SOAs) are controlled by list.SOAs/list.SOAs_practice
(e) Fontsize: this script uses Arial as it's a widely available font. The ideal fontsize in mm was determined using the longest stimuli
used in this script: personality. If you use different stimuli than the ones provided you need to figure out the appropriate fontsize in cm.
Go to FONTSIZE DETERMINATION and run block.FontsizeDetermination under the experiment with the longest stimuli (-> text.longestword) in your stimuli set.
Note the fontsize printed on the screen and use that size for parameters.fontheightCM under EDITABLE VALUES.
(f) Run block.determinefontsize under FONTSIZE DETERMINATION to make sure that the absolute distances used are correct for your monitor

Instructions

Instructions are not original to the task. They are provided by Millisecond
as htm pages and simple text elements and can be edited by changing
the provided html files and/or directly under Editable Instructions.

Summary Data

File Name: parafovealpriming_summary*.iqdat

Data Fields

Raw Data

File Name: parafovealpriming_raw*.iqdat

Data Fields

Parameters

The procedure can be adjusted by setting the following parameters.