As a baseline, we employed a cognitively-demanding number judgeme

As a baseline, we employed a cognitively-demanding number judgement task, again taken from previous neuropsychological, TMS and fMRI studies. On each trial, participants were presented with a probe number between 1 and 99, along with three numerical choices. They were instructed to select the number closest in value to the probe. Previous

studies have found that this Dapagliflozin molecular weight task was similar in difficulty (in terms of reaction time) to the most demanding synonym judgements (Hoffman et al., 2010 and Pobric et al., 2009). Therefore, the baseline task required similar levels of attention and general cognitive effort, but minimal semantic processing. Number judgement trials were also preceded by a sentence cue (see Table 1).

Therefore, neural processes involved in reading and comprehending the cues were equivalent across all conditions including the baseline, ensuring that differences would only emerge in the judgement phase. Each trial began with a fixation cross presented in the centre of the screen for 500 msec, which was followed by the cue. Participants were instructed to read the cue carefully and to press a button on the response box when they had finished reading. The cue remained on screen for 5000 msec. The judgement probe and three choices were then presented and participants responded by pressing one of three buttons on a response box held in their right hand. The stimuli remained on screen for 4000 msec, at which point the next trial began. Stimuli

were presented in blocks of two trials (total duration = 19 sec) GSK126 molecular weight with the two trials in each block being taken from the same experimental condition. There were 150 blocks in total and blocks from different conditions were presented in a pseudo-random order. A fixation block of 19 sec, in which no stimuli were presented, occurred after every five blocks of task. We used a blocked design to maximise power; however, this did introduce a degree of predictability in the order of contextual versus irrelevant cues. This is important as it could influence participants’ processing of the cues. If a participant became aware that irrelevant cued trials occurred in pairs, they might process the cue less fully on the second trial of the pair. In many reality, this is less of a problem than one might expect, for the following reasons. First, blocks followed one another continuously, making it hard to detect when a new block was starting. Second, sometimes two blocks of the same cue type were presented consecutively, making it harder for participants to recognise the blocked structure. A key aim of the study was to assess concreteness effects in the ventral anterior temporal lobe (vATL). Imaging this area with conventional gradient-echo fMRI is affected by magnetic susceptibility artefacts and other technical limitations that result in signal drop-out and distortion (Devlin et al., 2000 and Visser et al., 2010).

Leave a Reply

Your email address will not be published. Required fields are marked *

*

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>