Movement in the ipsilesional hand is segmented following unilateral brain damage

Unilateral stroke results in hemiplegia or hemiparesis of the contralateral side of the body. The ipsilateral side of the body, the so-called "good" side, is often assumed to have no deficit. However, there is increasing evidence that the function of the unaffected limbs, especially the upper extremities, is different from that of normal age-matched controls. In the present study, we examined the motor control of both hands of chronic stroke subjects, 6 with left hemisphere brain damage (LHBD) and 5 with right hemisphere brain damage (RHBD). The control group consisted of 5 normal age-matched subjects. The task of the subject was to move a handle by flexing his/her fingers until the target position was reached. The target position was set as 33% of the range of each subject. No time constraints were imposed. The movements of the normal subjects were basically smooth, with few hesitations. In contrast to this, the movements of both hands in the two stroke groups were segmented and characterized by multiple starts and stops. As compared to normals, the time to reach the target, the number of pauses during the movement, and the percent of time spent in pauses, were significantly greater for both hands of the LHBD group. In the RHBD group, the percent of time spent in pauses was significantly greater than the control group for the ipsilesional hand. The increased segmentation seen in the movements of the ipsilesional, as well as the contralesional. hands of the hemiplegic subjects suggests that the motor deficits in stroke patients may be due to a global inability to correctly plan and carry out movements.     

Binding object features to locations: Does the “spatial congruency bias” update with object movement?

One of the fundamental challenges of visual cognition is how our visual systems combine information about an object’s features with its spatial location. A recent phenomenon related to object–location binding, the “spatial congruency bias,” revealed that two objects are more likely to be perceived as having the same identity or features if they appear in the same spatial location, versus if the second object appears in a different location. The spatial congruency bias suggests that irrelevant location information is automatically encoded with and bound to other object properties, biasing perceptual judgments. Here we further explored this new phenomenon and its role in object–location binding by asking what happens when an object moves to a new location: Is the spatial congruency bias sensitive to spatiotemporal contiguity cues, or does it remain linked to the original object location? Across four experiments, we found that the spatial congruency bias remained strongly linked to the original object location. However, under certain circumstances—for instance, when the first object paused and remained visible for a brief time after the movement—the congruency bias was found at both the original location and the updated location. These data suggest that the spatial congruency bias is based more on low-level visual information than on spatiotemporal contiguity cues, and reflects a type of object–location binding that is primarily tied to the original object location and that may only update to the object’s new location if there is time for the features to be re-encoded and rebound following the movement.     

The Reciprocity-Arousing Potential of the Requester's Occupation and Helping Behavior

In a field experiment, 90 subjects were contacted by phone and asked by an experimenter to make a phone call for him notifying his employer that he would be late for work. The experimenter presented himself as a (1) physician vs. accountant (high social status occupations), (2) youthcounsellor vs. insurance salesman (medium social status occupations), or (3) fireman vs. gas-stationattendant (low social status occupations). It was found that subjects helped more frequently requesters in occupations of high potential for reciprocityarousing behavior (e.g., a physician) than of low potential (for reciprocityarousing behavior) (e.g., an accountant), regardless of the social status of the occupations.     

Action/inaction regret as a function of severity of loss

Two studies were conducted to examine whether people who experience severe losses tend to regret their failures to act more than people that experience less severe losses. Two time points were considered, after the event (short term), and a year later (long term). In Study 1, participants responded to scenarios depicting losses varying in degree of severity. As hypothesized, protagonists in the heavy loss cases were attributed with more regrets of omission (inaction) both in the short and in the long term. In the less severe loss scenarios, action regrets decreased significantly in the long term. In Study 2, one of the severe loss scenarios from Study 1 was presented with a less severe outcome. As expected, participants generated more inaction regrets in the severe loss version. Severity of loss influenced the preference for omission regrets in both studies for the short term and the long term. Copyright © 2002 John Wiley & Sons, Ltd.     

On the border: perimeter patrolling as a transitional exploratory phase in a diurnal rodent,the fat sand rat (<Emphasis Type="Italic">Psammomys obesus</Emphasis>)

Exploration is an initial phase of constructing spatial representation. In an illuminated environment, exploration by nocturnal rodents takes the form of home-base behavior, with the rodents organizing their activity in relation to the base, repeatedly orienting and returning to it. In the dark, home base behavior in gerbils is preceded by looping exploration, in which travel paths tangle into loops that close at various locations so that the gerbils pilot from one loop to the next. In the present study we tested a diurnal gerbil, the fat sand rat, Psammomys obesus, in both a lit and a dark open field in order to compare its exploratory behavior with that of nocturnal rodents. We found that under lit conditions, fat sand rats used perimeter patrolling, traveling mainly along the walls of the open field. In perimeter patrolling the animal probably monitors its location in relation to the perimeter (arena walls), and not to a specific location as in home base. In the dark, fat sand rats first used looping, and gradually shifted to perimeter patrolling exploration. We suggest that perimeter patrolling is a transient phase in which the animal evaluates possible locations for a home base. Thus, perimeter patrolling is an intermediate phase between looping, which is based on piloting from one landmark to the next, and home base exploration, in which the animal continuously orients to a specific location. This spatial behavior of perimeter patrolling may shed light on phases of information processing and spatial representation during exploration and navigation.     

Reflexive orienting by central arrows: Evidence from the inattentional blindness task

It was demonstrated that central arrows produce orienting of attention even when they are nonpredictive as to the target location. This finding was suggested to indicate reflexive orienting of attention by central arrows. However, it is not clear whether central arrows can produce an attentional effect without awareness. In two experiments, using a variation of the inattentional blindness task, we examine whether orienting of attention by a central arrow can be demonstrated without conscious perception of the arrow. We found that attention could be directed to the cued location even when the arrow was not consciously perceived.