Permanence and change in memory II. Reproduction of words in sentences

Abstract.— A retroactive interference paradigm was employed for studying qualitative memory changes. Sentences, containing an ambiguous word that was defined differently by succeeding words, were used as stimulus material. Such retroactive definitions of meaning were found to lead to qualitative changes in reproduction. It is suggested that the issue of permanence and change in memory may be related to the choice of lists of independent items or contextual units as stimulus material. A contextual theory of memory, implying the conception of memory in a stream, is advocated.     

How Discrimination Impacts Sociopolitical Behavior: A Multidimensional Perspective

The conventional wisdom regarding the impact of discrimination on political behavior is that the perception of prejudiced treatment motivates individuals to take political action. This study challenges this common conception by demonstrating that the source of discrimination can play a significant role in whether perceived or experienced injustice leads to activism or withdrawal from sociopolitical life. Drawing from political science and social psychology literature, this study provides a new perspective on the potential effects of discrimination on a relatively new marginalized group in the United States. Specifically, an important distinction is drawn between political (systematic) and societal (interpersonal) discrimination in analyzing the sociopolitical behavior of American Muslims in the aftermath of the 9/11 terrorist attacks. The results will hopefully encourage scholars to take a deeper look at the nexus between discrimination and democratic engagement, which is an important, complex, multidimensional, and understudied topic.     

The Shoulder and Elbow Joints and Right and Left Sides Demonstrate Similar Joint Position Sense

Proper orientation of the shoulder and elbow is necessary for accurate and precise positioning of the hand. The authors’ goal was to compare these joints with an active joint position sense task, while also taking into account the effects of joint flexion angle and arm dominance. Fifteen healthy subjects were asked to replicate presented joint angles with a single degree of freedom active positioning protocol. There were no significant differences in angular joint position sense errors with respect to joint (shoulder vs. elbow) and side (left vs. right). However, when considering linear positioning, errors were lower for the elbow, due to a shorter lever arm. Also, as flexion angles increased toward 90°, there was a consistent pattern of lower errors for both joints.     

Shoulder joint position sense improves with external load

Joint position sense (JPS) is important in the maintenance of optimal movement coordination of limb segments in functional activities. Researchers have shown that the sensitivity of musculotendinous mechanoreceptors increases as muscle activation levels increase. In the present study, when 25 participants tried to replicate the same presented position, both vector and elevation angle repositioning errors decreased linearly as the external load increased up to 40% above unloaded shoulder torque. However, external load had no effect on plane repositioning error. The results indicated that JPS increased under conditions of increasing external load but only in the direction of the applied load. That finding indicates that JPS acuity improves as muscle activation levels increase.