New Research From Psychological Science

Read about the latest research published in Psychological Science:

A Dissociation of Performance and Awareness During Binocular Rivalry

Daniel H. Baker and John R. Cass

In binocular rivalry, a different image is shown to each eye and awareness of the images alternates between eyes over time. Interestingly, researchers find that people still show some sensitivity to images presented to the suppressed eye. To determine how this might happen, the researchers measured participants’ sensitivity to probes presented to a single eye during periods of suppression or dominance. They found a high level of accuracy during suppression and determined that performance during suppressed periods was due not to probe-induced switches in rivalry dominance but rather to blindsight-like behavior in normal adults.

Saccades Toward the Target Are Planned as Sequences Rather Than as Single Steps

Jelmer P. De Vries, Ignace T. C. Hooge, and Frans A. J. Verstraten

Are scan paths planned in advance, or is each eye movement — also known as a saccade — in a scan path planned individually? Participants were instructed to move their eyes from a fixation point to a target in a high-contrast or low-contrast display. The display remained static throughout the trial (no-switch condition), or the target changed location during the participant’s first saccade (switch condition). Participants were unable to change their saccade path in the low-contrast switch condition but were able to in the high-contrast switch condition. Because high-contrast displays are processed faster than low-contrast displays, the results indicate that saccade paths are planned ahead and path changes depend on being able to process new information quickly.

Nonconscious Learning From Crowded Sequences

Anne Atas, Nathan Faivre, Bert Timmermans, Axel Cleeremans, and Sid Kouider

Simple associations can be learned implicitly (i.e., without awareness); however, it is still not well understood whether this is true of more complex knowledge. Sequences of X’s and O’s were displayed in participants’ visual periphery, outside of conscious awareness. Certain sequences of X’s and O’s were associated with gains and others were associated with losses. Participants could choose to respond (“go”) or not to respond (“no-go”) to each letter sequence. “Go” responses to rewarding sequences were faster than “go” responses to punishing sequences, suggesting that sequence learning can occur in a nonconscious manner.

Tryptophan Promotes Interpersonal Trust

Lorenza S. Colzato, Laura Steenbergen, Erik W. de Kwaadsteniet, Roberta Sellaro, Roman Liepelt, and Bernhard Hommel

Can the amino acid tryptophan increase levels of trust? Participants were given an oral dose of tryptophan or a placebo before playing a trust game with a partner. In the trust game, one participant — the truster — was given money and could choose to give some to his or her partner — the trustee. Whatever money was given to the trustee was multiplied by a factor of three, and the trustee could then choose to give some of the money back to the truster. Trusters who had received a dose of tryptophan gave more money to trustees than did trusters who had received a placebo, demonstrating a possible effect of tryptophan on interpersonal trust.