Jared E. Miller, Laura A. Carlson, and J. Devin McAuley
Can the things we hear affect the ways we allocate visual attention? In the first of three experiments, participants watched a screen while listening to an auditory rhythm. A white dot appeared in a corner of the screen in synch, slightly out of synch, or very out of synch with the final auditory tone. Researchers measured the amount of time it took from the moment the dot appeared to the moment when participants initiated an eye movement toward the dot. Participants’ saccade latencies were significantly faster when the dot’s appearance coincided with the last tone. This finding suggests that the temporal distribution of visual attention can be altered by a rhythmic auditory stimulus.
Ilia Korjoukov, Danique Jeurissen, Niels A. Kloosterman, Josine E. Verhoeven, H. Steven Scholte, and Pieter R. Roelfsema
It is widely believed that perceptual grouping occurs in parallel across the visual scene and without attention; however, some studies have indicated that this process may actually be time-consuming and demand attention. Researchers tested the time course of explicit perceptual grouping by presenting participants with two cues superimposed on a picture. Participants had to indicate whether both cues fell on the same or a different object in the picture. Response times were longer when the cues in the picture were located farther away from each other. This finding suggests a different path to perception that begins with rapid object classification followed by a serial perceptual grouping phase.
Martijn E. Wokke, Annelinde R. E. Vandenbroucke, H. Steven Scholte, and Victor A. F. Lamme
Although the human visual system is able to complete the contours of occluded objects, researchers are still unsure how this occurs. Participants were shown two groups of four notched circles, one of which was arranged to create an illusory form of a square. Participants were then instructed to indicate which set of circles formed a square. Researchers applied transcranial magnetic stimulation to participants’ lateral occipital (LO) brain area or to area V1/V2 during the task. Disruption of the LO area 100 ms after stimulus onset and disruption of V1/V2 163-182 ms after stimulus onset both reduced performance on the task. This suggests that brain activation occurs in an inverse hierarchal fashion (V1/V2 following LO), indicating that feedback to V1/V2 contributes to perceptual completion.
Independent Effects of Adaptation and Attention on Perceived Speed
Katharina Anton-Erxleben, Katrin Herrmann, and Marisa Carrasco
Past research has shown that both adaptation and attention can alter sensitivity to visual stimuli, but it is not known whether these two mechanisms interact. Participants were briefly shown two visual stimuli (Gabor patches): one with grading that moved upward (the adaptor) and one with grading that moved rightward (the control). Next, a cue appeared in one of the locations previously occupied by a patch. Two new Gabor patches then appeared, both with grading that moved upward. Participants were instructed to identify which patch was faster or slower. The researchers found that fast-moving adaptors decreased the perceived speed of subsequent stimuli, whereas slow-moving adaptors did not alter perceived speed. Attention increased perceived speed regardless of the adaptation effect, suggesting that adaptation and attention affect perceived speed independently.