Materials
This study used two lists of items reconstructed from previous studies (Toyota et al., 2007; 2013). Each list included 16 word pairs and 2 buffer pairs. These word pairs were constructed using two combinations of pleasant (e.g., happiness) and neutral words (e.g., dress) and unpleasant (e.g., war) and neutral words. These words were selected from items tested in a previous study (Hyodo et al., 2003). Two types of choice conditions were provided: self-choice and force-choice. In each choice condition, two types of word pairs were provided: pleasant–neutral (e.g., happiness–dress) and unpleasant–neutral (e.g., war–air) pairs. Each target was familiar and written in JapaneseKanji characters on a separate booklet page. Examples of each page corresponding to each condition as a function of the type of choice, type of word pair, and type of criterion are shown in Figure 1.
On each self-choice condition page, a word pair and a question corresponding to each type of choice and criterion were presented. However, on each page of the forced-choice condition, a word pair was presented, and one word in a pair was underlined, which was to be recalled. Assignment to the underlined word in each pleasant–neutral pair was fixed to a pleasant word in the pleasantness criterion and a neutral word in the unpleasantness criterion. This was since pleasant words may be chosen in the self-choice condition if the participants were asked to choose more pleasant words (words they like better) in each pleasant–neutral pair. In contrast, in each unpleasant–neutral word pair, the underlined word was fixed to an unpleasant word in the unpleasantness criterion and a neutral word in the pleasantness criterion because the unpleasant words may be chosen in the self-choice condition if the participants were asked to choose a more unpleasant word (the word that they dislike more) in each unpleasant-neutral pair.