Knowledge that Transforms

Neurologically intact adults perseverate in immediate serial recall, intruding items from a previous trial into the current response. We applied the electroencephalogram/event-related-potential subsequent-memory paradigm to immediate serial recall to investigate the causes of these errors. In line with previous studies using this paradigm, results revealed that words that were correctly recalled elicited a greater frontal positivity during encoding when compared with words that were either perseverated over or not produced for some other reason. More surprisingly, differences were also found at encoding between the words perseverated into the subsequent response and words that were not perseverated. These findings support a theory stating that abnormalities in both how the current target and the previous trial are processed can contribute to perseveration errors. These results inform existing theories of immediate serial recall and theories of the control of irrelevant information.

Many activities, such as driving or playing sports, require simultaneous monitoring of multiple, often moving, objects. Such situations tap people's ability to attend selected objects without tracking them with their eyes--this is known as attentional tracking. It has been established that attentional tracking can be affected by the physical speed of a moving target. In the experiments reported here, we showed that this effect is primarily due to apparent speeds, as opposed to physical speeds. We used sensory adaptation--in this case, prolonged exposure to adapting stimuli moving faster or slower than standard test stimuli--to modulate perceived speed. We found performance decrements and increments for apparently sped and slowed test stimuli when participants attempted attentional tracking. Our data suggest that both perceived speed and the acuity of attention for moving objects reflect a ratio of responses in low-pass and band-pass temporal-frequency channels in human vision.

A voluminous literature has examined how primates respond to nonverbal expressions of status, such as taking the high ground, expanding one's posture, and tilting one's head. We extend this research to human intergroup processes in general and interracial processes in particular. Perceivers may be sensitive to whether racial group status is reflected in group members' nonverbal expressions of status. We hypothesized that people who support the current status hierarchy would prefer racial groups whose members exhibit status-appropriate nonverbal behavior over racial groups whose members do not exhibit such behavior. People who reject the status quo should exhibit the opposite pattern. These hypotheses were supported in three studies using self-report (Study 1) and reaction time (Studies 2 and 3) measures of racial bias and two different status cues (vertical position and head tilt). For perceivers who supported the status quo, high-status cues (in comparison with low-status cues) increased preferences for White people over Black people. For perceivers who rejected the status quo, the opposite pattern was observed.

The perception of verticality is critical for balance control and interaction with the world. But this complex process fails badly under certain circumstances-usually as the result of an illusion. Here, we report on a real-world example of how the brain fails to disregard body position on a moving mountain tram and adopts an inappropriate frame of reference, which prompts passengers to perceive skyscrapers leaning by as much as 30°. To elucidate the sensory origin of this misperception, we conducted field experiments on the moving tram to systematically disentangle the contributions of four sensory systems known to affect verticality perception, namely, vestibular, tactile, proprioceptive, and visual cues. Our results refute the intuitive assumption that the perceived tilt of the buildings is based on visual error signals and demonstrate instead that a unified percept of verticality is a product of the synergistic interaction among multiple sensory systems and the contextual information available in the real world.

WOS:000324403000032

In the research reported here, we proposed and demonstrated the prediction-specificity effect, which states that people's prediction of the general outcome of an event (e.g., the winner of a soccer match) is less accurate when the prediction question is framed in a more specific manner (e.g., guessing the score) rather than in a less specific manner (e.g., guessing the winner). We demonstrated this effect by examining people's predictions on actual sports games both in field and laboratory studies. In Study 1, the analysis of 19 billion bets from a commercial sports-betting business provided evidence for the effect of prediction specificity. This effect was replicated in three controlled laboratory studies, in which participants predicted the outcomes of a series of soccer matches. Furthermore, the negative effect of prediction specificity was mediated by participants' underweighting of important holistic information during decision making.

Despite the central role of learning in visual recognition, it is largely unknown whether visual form learning is maintained in older age. We examined whether training improved performance in both young and older adults at two key stages of visual recognition: integration of local elements and global form discrimination. We used a shape-discrimination task (concentric vs. radial patterns) in which young and older adults showed similar performance before training. Using a parametric stimulus space that allowed us to manipulate global features and background noise, we were able to distinguish integration and discrimination processes. We found that training improves global form discrimination in both young and older adults. However, learning to integrate local elements is impaired in older age, possibly because of reduced tolerance to external noise. These findings suggest that visual selection processes, rather than global feature representations, provide a fundamental limit for learning-dependent plasticity in the aging brain.

>> This report constitutes a critical expansion of a recent study on tool use (Carlson, Alvarez, Wu, & Verstraten, 2010), published in this journal. Carlson et al. explored the classic question of how, during manipulation, an external object may seem to become an extension of one’s body. They demonstrated that objects manipulated with the hand can become one with the body, but objects manipulated with a tool cannot. They interpreted this as evidence that such integration is limited to first-order extensions. However, close inspection of the experimental conditions reveals that Carlson et al. overlooked how dynamic manipulation of an object affects the prehensile system. They used just one tool: a pair of grippers fixed to, and supported by, a table. In this arrangement, the table absorbs most of the forces associated with object manipulation. By contrast, when a freely maneuverable handheld tool is used, the forces are transmitted through the tool and interact with the arm and body, much as they do during direct manual manipulation. The notion that, without vision, object properties such as the length of a handheld rod can be perceived during dynamic manipulation has been well established. This system of touch perception is known as dynamic touch— perception based on information from effort-related muscle and tendon deformations (Carello & Turvey, 2000; Gibson, 1966; Turvey, 1996; Turvey & Carello, 2011). However, little is known about the perception of a target object when it is manipulated with a handheld tool. We concluded that the approach used by Carlson et al. would be a useful way to test such perception empirically, and we extended their conditions to include one with a freely maneuverable tool. Moreover, we predicted that the target object would be perceived with and without a tool, but only when the prehensile limb was maneuvering freely.