Ellen, Providence, Regina en New Astoria: een hotel-historie

<p><b>Experiment overview (a) and experimental design (b) for Experiment 2.</b> The general trial structure and experimental design of Experiment 2 are largely a replication of Experiment 1.</p

Early-latency cueing effects.

<p>a) results from Experiment 1. An occipitally distributed N1 component, elicited by shift-inducing cues, was larger over the contralateral hemisphere and smaller over the ipsilateral hemisphere, compared to the N1 elicited by non-informative cues. a) results from Experiment 2. In addition to replicating the N1 attention effect, we also observed a significant P1 modulation here that preceded the N1 in time. This P1 effect was found mainly over the ipsilateral hemisphere and is characterized by a more parietal scalp distribution than the subsequent N1.</p

Mean Response times and hit-rates.

<p>a) results from Experiment 1. At intermediate and long SOAs between cue and target stimuli, a classical cueing effect can be observed, whereas at shorter SOAs, responses to targets that were preceded by a non-informative cue took somewhat longer to process that those preceded by either a valid or an invalid cue. Hit rates did not differ significantly between conditions. b) results from experiment 2. Note that response times and accuracies to the validly cued peripheral targets and those to the centrally cued targets did not differ significantly from each other, but that responses in these two conditions were faster and more accurate than those to invalidly cued peripheral targets.</p

Additional cue-related effects in Experiment 2.

<p>(a) Cueing effects as a function of SOA condition. In all three SOA conditions, the shift-inducing and stay-central cues elicited similar positive deflections within the approximate 250–450 ms time window indicating that the shift-related positivity was no longer present in experiment 2, and these components were similar across SOA conditions. (b) Comparison of ERPs elicited by left . vs. right attention-shift inducing cues. Significant interaction between Cue Direction and Hemisphere over electrodes P7 and P8 indicate the presence of an EDAN component in these data. In addition, with a somewhat later onset, an ADAN component can also be observed. The plots in panel (b) are based on left vs. right hemisphere data (i.e. prior to transposing to ipsi- vs. contralateral positions).</p

Longer latency cueing effects.

<p>a) results from Experiment 1. From about 200 to 400 ms after cue-onset, the ERPs elicited by shift inducing cues were positively shifted, relative to the ERPs elicited by non-informative cues. At longer latencies, a clear distinction between cues predicting and easy target and cues predicting a difficult target can be seen; whereas for cues predicting an easy target the ERP wave form was more positive for shift inducing cues, whereas this was not the case for cues predicting a difficult target. This effect can in particular be observed over the contralateral hemisphere. b) results from experiment 2. Two effects can be noted here. First, an early latency cueing effect was present for cues predicting an easy target. At longer latencies, the ERPs elicited by stay-central cues are positively displaced, starting at around 500 ms after cue onset, whereas no such positive displacement can be observed for shift-inducing cues. Notably, this effect was larger for cues predicting an easy target than for cues predicting a difficult target.</p

Behavioral performance during scanning.

<p>Bars represent mean reaction times with color singleton present (dark bars) and absent (light bars) for the diffuse attention and the focused attention condition. Asterisks indicate significant differences between the focused and the diffuse condition and between the absent and present trials in the diffuse condition.</p

ROIs in early visual areas V1, V2 and V3.

<p>Shown are the ROIs in the right hemisphere of one participant for the distractor location in the upper left visual field, as determined by our mapping procedure.</p

Layout of the currently used paradigm.

<p>From bottom to top, the succession of events within a trial is shown. Participants initially attended to the RSVP stream in the middle of the display. Depending on the condition, they either had to detect the letter “K” or the letter “I” that served as a go-signal. Left panel: an example stimulus sequence of the focused condition when a color singleton distractor (dotted circle) was present. After the letter K was presented (70% of all trials), participants had to respond to the line-element in the diamond. Note that the go-signal in the focused condition was presented at search display onset. Center panel: Shown here is an example of the diffuse attention condition when a color singleton distractor was present with the first go-signal I. After the letter I was presented (85% of all trials), participants had to respond to the line-element in the diamond but only when the display elements made up a circle. Right panel: When the display elements made up a square (15% of all trials), participants had to withhold their response. Note that the first go-signal in the diffuse condition was presented before search display onset.</p

Figure 4

<p>(a) Event related averages of the fMRI responses. Shown are the averages to the color singleton in the diffuse attention (solid line) and the focused attention condition (dotted line) in V1, V2 and V3, collapsed across quadrants and participants. In V3, activity in response to the color singleton was significantly higher at TR1 and TR2 (shaded area) in the diffuse attention condition relative to the focused attention condition. (b) Mean percent signal change in V1, V2 and V3. Shown are mean signal change collapsed over TR1, TR2 and TR3 for the diffuse attention (black bars) and focused attention condition (white bars). In V3, mean activity in the diffuse condition in response to the color singleton was significantly higher than mean activity in the focused condition. In addition, the activity induced by the color singleton increased from V1 to V3 when the attentional window was wide.</p

Stimulus material: 240 Swahili words.

<p>Stimulus material: 240 Swahili words.</p