Experimental materials and results.

<p>(A) Examples of search displays in the control condition (left panel) and the pop-out distractor condition (right panel). Participants were instructed to search for the tilted pop-out target and to ignore an occasionally occurring luminance pop-out distractor. (B) Left panel: Mean interference effects (reaction time on pop-out distractor trials minus reaction time on control trials) as a function of valence state (negative, positive) and arousal state (high, low). Right panel: Mean conflict-adaptation effects (interference on trials following pop-out distractor trials minus interference on trials following control trials) as a function of valence state (negative, positive) and arousal state (high, low). Error bars indicate standard errors.</p

Grand averaged event-related brain potentials elicited in response to color-defined (pop-out) targets at electrodes PO7/PO8.

<p>(a) Waveforms contra- and ipsilateral to the singleton location. (b) Topographical maps of PCN scalp distributions for each of the three Salience conditions (High, Middle, Low) at the point in time when the difference between contra- and ipsilateral waveforms reached its maximum. These maps were computed by mirroring the contra-ipsilateral difference waves to obtain symmetrical voltage values for both hemispheres (using spherical spline interpolation). (c) PCN difference waves obtained by subtracting ipsilateral from contralateral activity for each of the three Salience conditions (High, Middle, Low).</p

Behavioural results.

<p>(a) Reaction times (lines) and error rates (bars) as a function of Saliency (High, Middle, Low) for orientation-defined (pop-out) targets. (b) Reaction times (lines) and error rates (bars) as a function of Saliency (High, Middle, Low) for color-defined (pop-out) targets.</p

Grand averaged event-related brain potentials elicited in response to orientation-defined (pop-out) targets at electrodes PO7/PO8.

<p>(a) Waveforms contra- and ipsilateral to the singleton location. (b) Topographical maps of PCN scalp distributions for each of the three Salience conditions (High, Middle, Low) at the point in time when the difference between contra- and ipsilateral waveforms reached its maximum. These maps were computed by mirroring the contra-ipsilateral difference waves to obtain symmetrical voltage values for both hemispheres (using spherical spline interpolation). (c) PCN difference waves obtained by subtracting ipsilateral from contralateral activity for each of the three Salience conditions (High, Middle, Low).</p

Stimulus displays used in the present visual pop-out binary localization task.

<p>Participants were required to give a speeded forced-choice response indicating the position (left vs. right hemi-field) of the feature singleton, which was selected randomly from one of the six lateral positions on the middle circle.</p

Experimental design and stimuli.

<p>(a) A search display, consisting of 39 broken grey bars arranged around three imaginary concentric circles, was presented in the center of the screen, on a black background. There was always an orientation target; and in half of the trials (randomly determined), there was also a luminance distractor. Each trial started with a white fixation spot that was hidden while the display was presented until response. Inter-stimulus-intervals varied randomly in the range 900±200 ms. While ignoring a bright distractor, participants searched for a tilted target bar and decided, via a speeded button press, whether the gap was located at the top or the bottom of the bar. This response decision required focal attention to be allocated to the target. (b) 25 Salience difference conditions resulted from 5 orientation (7, 8, 9, 14, 45°) and 5 luminance (13.8, 14.8, 17.9, 19.4, and 25.5 cd/m²) contrasts.</p

Empirical data of the baseline salience measurement and data fitted by the accumulator salience model.

<p>Left panel: five salience levels of orientation targets. Right panel: five salience levels of luminance targets. Symbols depict RT quantiles of each condition as follows: o = .1, Δ = .3, + = .5, × = .7, and ◊ = .9. Lines represent RTs generated by the model. Fitted RTs differ from empirical RTs by 5 ms on average (range: 0 to 28 ms). Additional parameter estimates were <i>T</i>_er = 300 ms, <i>s</i>_er = 70 ms, a = .08, and β = .294.</p

Course of BIC dependent on the inflection point of the regression function.

<p>Regression functions were fitted according to formula (1), with the inflection point as fixed parameter. Inflection points are specified in ms of salience difference.</p

Parameter estimates of the model predictions fitted to empirical and modeled data.

<p><i>Note: n</i> = 25. Estimate for empirical data in ms; asymptote estimate for modelled data in proportions. <i>R</i>_i = Nonlinear regression function. <i>S.E.</i> = Standard Error. <i>t</i> and <i>p</i> = value and probability of the t statistic associated with parameter estimate. Degrees of freedom: R₁: 23, R₂: 22. <i>CI</i> = 95% confidence interval. <i>BIC</i> = Bayes Information Criterion.</p

Capture of the eye by less salient distractors.

<p>Empirical proportion of capture by the distractor, averaged across participants, represents the proportion of first eye movements landing on the distractor position. Salience difference, averaged across participants, was derived from detection times in the baseline salience measurement requiring a simple target-present vs. target-absent decision (see <i>Methods</i> of <i>Behavioral eye-tracking experiment</i>). Negative x-values indicate distractors less salient than the target. Dots represent mean values of proportion of capture for each salience difference condition (<i>n</i> = 2); arrows indicate the associated standard errors.</p