Attending to a misoriented word causes the eyeball to rotate in the head

Torsional eye movements are triggered by head tilt and a rotating visual field. We examined whether attention to a misoriented form could also induce torsion. Thirty-six observers viewed an adapting field containing a bright vertical Une, and then they viewed a display that was composed of two misoriented words (one rotated clockwise, the other counterclockwise, by 15°, 30°, or 45°). The subjects were instructed to attend to one of the words. The subjects’ adjustments of a reference line to match the tilt of the afterimage showed that attention to a misoriented word produces torsional eye movement (verified with direct measurements on 4 additional subjects). This eye movement reduces the retinal misorientation of the word by about 1°. The results of this study reinforce the linkage between selective attention and eye movements and may provide a useful tool for dissecting different forms of “mental rotation” and other adjustments in internal reference frames. Apparent-motion displays confirming that the eye rotated in the head may be downloaded from www.psychonomic.org/archive.     

Filling a gap in the semantic gradient: Color associates and response set effects in the Stroop task

In the Stroop task, incongruent color associates (e.g., LAKE) interfere more with color identification than neutral words do (e.g., SEAT). However, color associates have historically been related to colors in the response set. Response set membership is an important factor in Stroop interference, because color words in the response set interfere more than color words not in the response set. It has not been established whether response set membership plays a role in the ability of a colorassociate to interfere with color identification. This issue was addressed in two experiments (one using vocal responses and one using manual responses) by comparing the magnitude of interference caused by color associates related to colors in the response set with that of interference caused by color associates unrelated to colors in the response set. The results of both experiments show that color associates unrelated to colors in the response set interfered with color identification more than neutral words did. However, the amount of interference was less than that from color associates that were related to colors in the response set. In addition, this pattern was consistent across response modalities. These results are discussed with respect to various theoretical accounts of Stroop interference.     

Spatial updating relies on an egocentric representation of space: Effects of the number of objects

Models of spatial updating attempt to explain how representations of spatial relationships between the actor and objects in the environment change as the actor moves. In allocentric models, object locations are encoded in an external reference frame, and only the actor’s position and orientation in that reference frame need to be updated. Thus, spatial updating should be independent of the number of objects in the environment (set size). In egocentric updating models, object locations are encoded relative to the actor, so the location of each object relative to the actor must be updated as the actor moves. Thus, spatial updating efficiency should depend on set size. We examined which model better accounts for human spatial updating by having people reconstruct the locations of varying numbers of virtual objects either from the original study position or from a changed viewing position. In consistency with the egocentric updating model, object localization following a viewpoint change was affected by the number of objects in the environment.     

Amygdala or hippocampus inactivation after retrieval induces temporary memory deficit

The hypothesis that memory is stored through a single stage of consolidation that results in a stable and lasting long-term memory has been challenged by the proposition that reactivation of a memory induces reconsolidation of the memory. The reconsolidation hypothesis is supported by evidence that, under some conditions, post-retrieval treatments affecting amygdala and hippocampus functioning impair subsequent retention performance. We now report that repeated retention testing attenuates the performance impairment induced by post-retrieval reversible inactivation of the amygdala and hippocampus of rats induced by tetrodotoxin. These findings challenge the reconsolidation hypothesis and suggest that the post-retrieval retention performance impairment is best explained as due to temporary retrieval failure.     

Cognitive load of navigating without vision when guided by virtual sound versus spatial language

A vibrotactile N-back task was used to generate cognitive load while participants were guided along virtual paths without vision. As participants stepped in place, they moved along a virtual path of linear segments. Information was provided en route about the direction of the next turning point, by spatial language ("left," "right," or "straight") or virtual sound (i.e., the perceived azimuth of the sound indicated the target direction). The authors hypothesized that virtual sound, being processed at direct perceptual levels, would have lower load than even simple language commands, which require cognitive mediation. As predicted, whereas the guidance modes did not differ significantly in the no-load condition, participants showed shorter distance traveled and less time to complete a path when performing the N-back task while navigating with virtual sound as guidance. Virtual sound also produced better N-back performance than spatial language. By indicating the superiority of virtual sound for guidance when cognitive load is present, as is characteristic of everyday navigation, these results have implications for guidance systems for the visually impaired and others.     

The genetics of gambling and behavioral addictions

Behavioral addictions are considered as the repetitive occurrence of impulsive behaviors without consideration of their potential negative consequences. These addictions represent an increasing cost to society and are an important new field of research in psychiatric genetics. There has been a growing body of evidence on the familial aggregation and genetic influences on the development of behavioral addictions and mainly on pathological gambling. The aim of this article is to critically review findings of family and molecular genetic studies on behavioral addictions, focusing on pathological gambling and commenting on other disorders where appropriate. This review provides a comprehensive approach to genetic studies on behavioral addiction and points out the necessity of expanding the genetic research in this field. Future directions for genetic studies in this field are also discussed.