IDENTIFICACIÓN DE IMPACTOS AMBIENTALES

All participants who volunteered for the experiment attended two separate sessions. The participants were to come back for the second session between 36 and 60 hours after they had done the first session, any earlier or later than this time frame was considered as failing to complete the experiment. How the experiment proceeded is outlined in Table 5.5. This example shows

presentations where word pairs were given first; this was randomised across participants.

Table 5.5. Procedures within the experiment sessions.

Session I Session II

Study Phase – word-pairs

10-minute break Immediate cued-recall – word-pairs A short break, if wish Study phase – picture-pairs

10-minute break Immediate cued-recall – picture-pairs

[End of the session]

Delayed recognition – word-pairs

Delayed cued-recall – word-pairs A short break, if wish Delayed recognition – picture-pairs

Delayed cued-recall – picture-pairs

[Experiment Finished]

Before starting the study phase, instructions and a brief practice

containing 10 mock trials were given to the participants. As mentioned earlier, all participants experienced both sets of stimuli (word-pairs and picture-pairs), which were done separately, in the same session. The order of which set of stimuli was presented to participants first was counterbalanced. That is, in the first session, half of the participants received the task with word-pairs first whilst the other half began with picture-pairs.

In the first session, the participants were directed to do two study phases for word-pairs and picture-pairs respectively, and also two immediate cued- recall tasks of items from the different conditions. The participants were tested individually and, in the study phase for each condition (word/picture), each participant received 198 trials, including 30 initial presentations of the to-be-

learnt pairs, 90 follow-up cued-retrieval practices of the to-be-learnt pairs, and 78 filler pairs.

The study phase consisted of presentation trials of the to-be-learnt pairs as well as the intervening pairs, and cued-retrieval practice trials of the to-be- learnt pairs. The to-be-learnt pairs and intervening pairs were presented in the same way. On every trial, there was a brief (500 milliseconds) interstimuli

interval, during which a blank screen with a cross (+) in the middle of the screen appeared, between trials to remind participants the next trial was about to come up. The presentation trials showed the two items side by side on the screen for 4 seconds before being removed from the screen for the presentation of the next trial. In cued-retrieval practice trials, a cue was presented on the left of the screen along with three items, a filler, a semantically related distractor, and the target, on the right of the screen. Participants had a maximum of 10 seconds to choose one of the three items to match with the cue using a mouse-click on the item of their choice. Once a response was received, auditory feedback

(correct/wrong) was provided by the computer and the filler and the distractor were removed from the screen, leaving only the cue and the target. To ensure the participants realised that the target/correct response remained on screen, a red ‘√’ was displayed on the screen, next to the target at the same time as feedback was provided.

Stimuli for massed and spaced practice conditions were counterbalanced and randomised throughout. Figure 5.1 provides an example, for word-pairs, of how presentation trials and cued-retrieval practice trials were presented to the participants during the study phase. Each square in Figure 5.1 represents the screen layout that the participants saw for a trial. Massed practice involved an initial presentation of a word-pair or picture-pair and 3 immediate cued-retrieval practice trials. With spaced practice, on the other hand, each trial was spaced out by 4 intervening trials, which could be filler trials, a set of massed practice trials (initial presentation plus the follow-up cued-retrieval practices), or cued- retrieval practice trials of other spaced practiced pairs. The blank space between the squares in Figure 5.1 represents the inter-stimuli interval.

Figure 5.1. Presentations of trials in the study phase - linguistic stimuli. Once the study phase terminated, participants were given a ten-minute- break, during which they were engaged in general conversation, before

proceeding to an immediate cued-recall task. In the cued-recall task, all 30 to- be-learnt pairs were presented one by one with a cue on the left of the screen, and three choices, a distractor, a filler, and the target, on the right. The

participants were told that they had a maximum of 10 seconds for each trial and were required to choose one from the three items to match the cue that they had received by clicking on their item of choice. Participants were informed that no feedback would be given in this task and once they had clicked on an item of their choice, the next trial would be presented. The first half of the session finished on the completion of the immediate cued-recall task. Before moving on to the second half, the participants could take a break if they wished to do so. In the second half of the session, the participants were given the other set of stimuli to learn and the procedure was repeated starting with a study phase followed by a ten-minute-break, then the immediate cued-recall task.

Delayed recognition tasks and a delayed cued-recall tasks were

performed 2 days after completing the study phase; a delay interval at which a difference between massed and spaced practice has previously been reported (e.g. Balota et al., 2006; Karpicke & Roediger, 2007b). The word-pairs and picture-pairs were tested separately within the same session. Prior to the delayed recognition tasks, the participants were notified that some of the pictures or words were shown in the study phase and the others were not. The

participants were asked to judge whether they had seen each picture or word in the study phase or not. A mouse with ‘Yes’ (the left button) and ‘No’ (the right button) labels was fixed in front of the participants, they were directed to click on one of the buttons to give their response. In each delayed recognition task, 90 items were presented, including 30 target items (which had appeared four times during the study phase), 30 fillers (new items), and 30 distractors (which had appeared once in the study phase). For each item (a word or a picture), the participants had a maximum of 5 seconds to respond and the next item was presented after their response; a 500msec blank screen intervened between items. No feedback was given in the delayed recognition tasks.

On completion of the delayed recognition task, participants were

instructed to proceed to do the delayed cued-recall task, which was identical to the immediate cued-recall tasks. Participants could have a small break between delayed recognition tasks and the delayed cued-recall tasks if they so wished. 5.5. Results and Discussion

The analyses in this section were performed with SPSS, statistic software. Statistical significance was accepted at the level of 0.05 and lower; a significance value of 0.01 was considered to be highly significant. However, when a rigid value of significance (p value between 0.05 and 0.06) was spotted, it was treated as a significant value and follow-up tests(s) was applied. Effect size(s) was also reported using partial Eta squared provided by ANOVAs. Boxplots were used to demonstrate overall performance of the three groups of participants in certain experimental conditions. Outliers in the datasets, if any, were not eliminated from the analyses so that the data revealed potential individual difference among participants.