The Go/No-go Association Task

For the assessment of implicit positivity toward violence, one GNAT task was designed using E-Prime 1.1 software. The GNAT (Nosek & Banaji, 2001) is similar to the IAT in that it assesses the strength of association between a target category and an attribute, but different from it in that the GNAT allows the examination of automatic cognitive

association between a single target category (e.g., violence) and an attribute (e.g., pleasant – unpleasant). The GNAT is useful when one is interested in assessing the strength of

association between a single target and an attribute without the involvement of a contrasting object. During the critical blocks, target and distractor items are presented briefly one at a time in the middle of the computer screen, and participants are required to press the spacebar (‘Go’ response) if the word belongs to either of the two categories (e.g., violent or pleasant), the labels of which appear on the two upper corners of the screen, or to do nothing (‘No-go’ response) if the word does not belong to either category.

Four lists of word stimuli were used: 10 violent, 10 nonviolent, 10 pleasant, and 10 unpleasant (see Table 2.4). The selected words were chosen from an initial pool of words which were rated by 23 independent raters on their pleasantness-unpleasantness and whether they had a violent or nonviolent connotation. Words for which there was an interrater

agreement of 80% and over and were rated high on each dimension, were finally selected. The nonviolent words initially chosen, were later substituted by different ones after the pilot study described below (Section 7 in this chapter) indicated that some were confused as ‘pleasant’. The final word lists did not differ in terms of frequency or length (Table 1 in Appendix B). As the nonviolent words serve as noise throughout the task, the nonviolent word list was not matched for frequency and length to the other three lists. The N-Watch program was used in order to obtain the lexical statistics (Davis, 2005).

Table 2.4

Word Lists in the Violence Go/No-go Association Task

Violent Nonviolent Pleasant Unpleasant

Shoot Explain Glad Yucky

Attack Identify Cheerful Horrible

Stab Insert Fantastic Agony

Push Estimate Sweet Terrible

Hit Open Excellent Failure

Choke Walk Sun Ugly

Kick Advertise Happy Dirty

Punch Write Joy Evil

Beat Transfer Pleasure Nasty

Fight Distribute Smile Bad

6.2.1. Procedure of the GNAT. The GNAT begins with on-screen instructions which provide details about the task and instructions. Both speed and accuracy are highlighted. A screen with instructions is presented before the beginning of each block in order to prepare participants for the following categorisation condition (e.g., in the next block you will classify words as being either violent or pleasant). After the first two 1,000 ms blocks (B3 & B4) they read another screen preparing them for the 750 ms blocks (B5 & B6) by informing them that the task will get a little bit harder as the words will disappear faster from the screen.

The task comprises two conditions (violent words + pleasant words [VP], violent words + unpleasant words [VU]), each one consisting of two blocks, one with a response window of 1,000 ms and one with a response window of 750 ms, to ensure automaticity of responses without increasing the number of errors (Nosek & Banaji, 2001). Each block contains equal number of words from each one of the four categories (violent, nonviolent, pleasant, and unpleasant). Words are selected randomly and without replacement by E-Prime

software. There is a 250 ms interstimulus interval, during which participants receive feedback. If the response is correct, a green ‘O’ appears in the middle of the screen replacing the target word, or a red ‘X’ if the response is incorrect or the participant does not respond within the specified time limit. In incorrect trials participants also hear a beep tone from the computer speakers. This allows the experimenter to monitor their performance in order to stop and re­ administer the experiment in case of excessive errors. The labels of the categories are

presented in the upper left and right corners of the computer screen in white capital letters in 20 point Courier New font. The target words are presented in the centre of the screen in cyan lower case letters and have the same size and font as the categories words. The colour of the background is black.

The task begins with two practice blocks to familiarise participants with the procedure (see Table 2.5). In the first block participants have to discriminate between violent and

nonviolent words, and press the spacebar (‘Go’ response) only if the word that appears in the middle of the screen is a violent one. In the second block participants have to discriminate between pleasant and unpleasant words by responding only to the pleasant ones. The practice blocks have a 1,000 ms response window and consist of 20 trials, half of which are targets and half are distractors. After the practice blocks follows the GNAT, consisting of four test blocks, two for each condition (VP, VU) and for each response window (1,000 ms, 750 ms). Each test block comprises 16 practice and 40 critical items. On-screen instructions are presented before each block, and participants are instructed to respond (press the spacebar) only to those target words which belong to either of the two categories whose labels appear on the upper right and left corners of the computer screen, and do nothing when they see words which are not members of these two categories. Speed and accuracy are also emphasised.

Table 2.5

Blocks Sequence of the Violence Go/No-go Association Task

Block No. of trials ‘Go’ response ‘No-go’ response B1 practice 20 Violent words 1,000 ms B2 practice 20 Pleasant words 1,000 ms

B3 1st test block Violent OR

16 + 40

1,000 ms Pleasant words

B4 2nd test block Violent OR

16 + 40

1,000 ms Unpleasant words

B5 3rd test block Violent OR

16 + 40

750 ms Pleasant words

B6 4th test block Violent OR

16 + 40 750 ms Unpleasant words Nonviolent words Unpleasant words Nonviolent OR Unpleasant words Nonviolent OR Pleasant words Nonviolent OR Unpleasant words Nonviolent OR Pleasant words

6.2.2. Scoring of the GNAT. Only correct responses to trials that require a ‘Go’ response (target identification) are included in the analysis. The RTs in the two blocks (1,000 ms, 750 ms) for each condition (VP, VU) are averaged in order to obtain each participant’s mean RT for each condition. A difference score is then computed for each participant, by subtracting the mean RT in the VU condition from the mean RT in the VP condition (VP – VU). Positive scores indicate faster responses in the VU condition and negative scores indicate faster responses in the VP condition. A higher positive difference score indicates more negative association between violence and pleasantness, while a higher negative score a more positive association between violence and pleasantness. An alternative scoring method is the sensitivity index d’ from the Signal Detection Theory (Green & Swets, 1966). A greater d’ value indicates a better ability to discriminate targets from distractors. This means that if

one has a greater d’ in the VP condition than the VU condition, he/she is better able to discriminate violent and pleasant words among the distractors (nonviolent - unpleasant), indicating a stronger association between the two concepts. However, the use of response latency is considered a more reliable measure of performance and is preferred over sensitivity d’ (Nosek & Banaji, 2001). For this reason GNAT results in the studies that follow in this thesis will be analysed based only on response latencies.