Automatic capture of attention by flicker

Abstract

Visual motion captures attention, but little is known about the automaticity of these effects. Here, we tested if deviant flicker frequencies, as one form of motion, automatically capture attention. Observers searched for a vertical target among tilted distractors. Prior to the target display, a cue array of sinusoidally modulating (flickering) annuli, each surrounding one location of the subsequent target(-plus-distractors) display was presented for variable durations. Annuli either flickered all at 1 Hz (neutral condition, no-singleton cue), or a single annulus flickered at a unique frequency of 5 Hz, 10 Hz, or 15 Hz. The location of this singleton-frequency cue was uncorrelated with target location. Thus, we could measure benefits (target at cued location) and costs (target ≠ cued location) for cues of different frequencies and durations. The results showed that deviant flicker frequencies capture attention, as we observed benefits and costs, falsifying that nonspatial filtering accounted for the cueing effect. In line with automatic capture, cueing was effective in singleton (Experiment 1) and nonsingleton search tasks (Experiment 2), and is thus not dependent on ("top-down") singleton detection mode. Moreover, analysis of results ruled out trial-by-trial "swapping" of flicker frequencies from preceding target to subsequent distractor locations. Results also revealed increasing cueing effects with higher cue flicker frequency and longer duration. This indicates a significantly longer period of automatic capture by sinusoidal flicker than the typical inhibition of return observed around 250 ms after the onset of uninformative static or single-transient cues.

Keywords: Motion; attentional capture; automaticity.

Fig. 1

Illustration of the sequence of events for trials in Experiment 1 (top right display) and Experiment 2 (bottom right display). After a variable fixation duration, annuli were presented at eight locations and flickered sinusoidally around mean luminance. On half of the trials, the speed of flicker of a frequency-singleton cue (5 Hz, 10 Hz, or 15 Hz) differed from the nonsingleton annuli (1 Hz), while all annuli flickered at the same speed (1 Hz) in the remaining (i.e., neutral) trials. The cue display containing the flickering annuli was presented for either 180 ms or 380 ms. The subsequent target-search display remained on screen until a response was made. Participants indicated the color (green or red) of a single vertical line among homogeneous (Experiment 1) or heterogeneous (Experiment 2) distractor lines

Fig. 2

RT cueing effects (invalid minus valid, left panel), cueing benefits (neutral minus valid, central panel), and cueing costs (invalid minus neutral, right panel) as a function of the cue frequency (5 Hz, on the left; 10 Hz, in the center; 15 Hz, on the right of each respective panel), and duration (180 ms, broken lines; 380 ms; straight lines), with data averaged across Experiments 1 and 2. We observed both, significant benefits and costs at 10 Hz and 15 Hz cue frequencies. Error bars represent ±1 SE

Fig. 3

RT cueing benefits (neutral minus valid, left panel) and cueing costs (invalid minus neutral, right panel) as a function of the cue frequency (5 Hz, on the left; 10 Hz, in the center; 15 Hz, on the right of each respective panel), and duration (180 ms, broken lines; 380 ms; straight lines), with data averaged across Experiments 1 and 2, for trials following an n − 1 invalid trial only. Cueing benefits (neutral − valid) were larger than cueing costs (invalid − neutral) in these trials. Error bars represent ±1 SE