The effect of loading on position sense in the tongue

The position sense of the tongue and aftereffects on the position sense subsequent to loading were directly investigated. Nine subjects judged the straightahead with the tongue before and after straining laterally with the tongue against the horizontal force induced by a 29.5-g weight. Two of these subjects also participated in the experiment after the surface of the tongue had been anesthetized. Prior loading of the tongue biased the subjects' subsequent judgment of the straight-ahead; following loading, the tongue was placed farther in the direction of the previous effort. The results are discussed with reference to postcontraction effects from experiments on loading the limb and eye.     

Perception of Object Length by Sound

Although hearing is classically considered a temporal sense, everyday listening suggests that subtle spatial properties constitute an important part of what people know about the world through sound. Typically neglected in psychoacoustics research, the ability to perceive the precise sizes of objects on the basis of sound was investigated during the routine event of dropping wooden dowels of different lengths onto a hard surface. In two experiments, the ordinal and metrical success of naive listeners was related to length but not to the simple acoustic variables (duration, amplitude, frequency) likely to be related to it. Additional analysis suggests the potential relevance of an object's inertia tensor in constraining perception of that object's length, analogous to the case that has been made for perceiving length by effortful touch.     

Global stereopsis in rhesus monkeys

In three separate experiments an attempt was made to demonstrate global stereopsis in two rhesus monkeys by using random dot stereograms projected and viewed through polarizing filters. Although both animals learned a number of discriminations, control tests showed that both were perceiving non-depth cues such as monocular identification of minute pattern differences or brightness differences caused by reflections of polarized light. In a final experiment red/green anaglyph forms of the stereograms were viewed through red/green filters. Both monkeys, together with a third experimentally naive animal, showed incontrovertible evidence of prompt discrimination based on stereopsis. This paper makes a number of recommendations about the use of random dot stereograms to demonstrate global stereopsis in animals.     

Inside the opponent's head: perceived losses in group position predict accuracy in metaperceptions between groups

Members of groups in conflict typically perceive the same reality in opposing ways. We investigated individuals' ability to accurately perceive out-group members' views of the conflict. Drawing on research on power and metaperceptions, we hypothesized that perceiving losses to in-group position would increase accuracy in predicting out-group members' views. Study 1 was conducted immediately following the Gaza flotilla incident. Israelis, who perceived the event as causing political losses to their group, were more accurate in predicting out-group members' views of the incident than were Palestinians, who perceived the event as causing political gains for their group. Moreover, Israelis' accuracy increased with their perception of political losses for Israel, whereas Palestinians' accuracy decreased with their perception of political gains for Palestinians. These effects were particularly pronounced among those participants who were highly identified with their group. Study 2 replicated the relationship between perceived losses and accuracy, and demonstrated that it could not be accounted for by factors such as education, political orientation, or empathy.     

Human newborns match tongue protrusion of disembodied human and robotic mouths

No evidence had been provided so far of newborns’ capacity to give a matching response to 2D stimuli. We report evidence from 18 newborns who were presented with three types of stimuli on a 2D screen. The stimuli were video-recorded displays of tongue protrusion shown by: (a) a human face, (b) a human tongue from a disembodied mouth, and (c) an artificial tongue from a robotic mouth. Compared to a baseline condition, neonates increased significantly their tongue protrusion when seeing disembodied human and artificial tongue movements, but not when seeing a 2D full-face protruding tongue. This result was interpreted as revealing the exploration of top-heavy patterns of the 2D face that distracted infants’ attention from the tongue. Results also showed progressively more accurate matching (full tongue protrusion) throughout repeated exposure to each kind of stimulus. Such findings are not in line with the predictions of the innate releasing mechanism (IRM) model or of the oral exploration hypothesis. They support the active intermodal mapping (AIM) hypothesis that emphasizes not only the importance of repeated experience, as would the associative sequence learning (ASL) hypothesis, but also predicts a differential learning and progressive correction of the response adapted to each stimulus.     

Localization of tactile stimuli and body parts in space: two dissociated perceptual experiences revealed by a lack of constancy in the presence of position sense and motor activity

Two motor acts were analyzed at the level of tongue and fingers. These motor acts generated illusions. When subjects voluntarily rotated the tongue by 90 degrees, the perceived orientation of a tactile stimulus applied to the tongue did not covary with the perceived orientation of the tongue itself. Analogously, when subjects voluntarily crossed two adjacent fingers, the perceived position of two tactile stimuli applied to the fingers did not covary with the perceived position of the fingers themselves. Although tongue and fingers were positioned accurately in space, a lack of perceptual constancy occurred for tactile stimuli applied to these body parts. Therefore, whereas position sense was preserved, correct localization of objects was lost. The occurrence of this perceptual dissociation suggests that spatial localization of tactile stimuli may be independent both of knowledge of body part location and motor activity.     

Aging and working memory inside and outside the focus of attention: dissociations of availability and accessibility

Two experiments used the N-Back task to test for age differences in working memory inside and outside the focus of attention. Manipulations of the difficulty of item-context binding (Experiment 1) and of stimulus feature binding (Experiment 2) were used to create conditions that varied in their demand on working memory, with the expectation that greater demand might increase age differences in focus-switching costs and the search rate outside the focus of attention. Results showed, however, that although age differences were evident in measures of overall speed and accuracy, and the manipulations significantly affected response times and accuracy in the expected direction, the experimental manipulations had no impact on age differences. Findings instead pointed to age-related reductions in accuracy but not speed of focus-switching and search outside the focus of attention. Thus, age-related deficits appear to involve the availability of representations in working memory, but not their accessibility.     

Persistence during extinction: Are judgments of persistence affected by contingency information?

The partial reinforcement extinction effect (PREE), defined as increased behavioral persistence following intermittent reward, is considered an important outcome of instrumental learning contingencies, both inside and outside the laboratory. Since adults have a rich experience with situations in which desired outcomes depend on instrumental responding, we asked whether that experience affects judgments of persistence when relevant contingency information is manipulated. Subjects read simple scenarios with information about behaviors generated by high vs. low reward rate, and then judged the resultant persistence of these behaviors under no-reward conditions. Studies 1 and 2 found no evidence that persistence judgments were affected by contingency information in naive subjects. Studies 3 and 4 compared groups with and without explicit knowledge about behavioral psychology and thus tested possible effects of that knowledge for persistence more directly. Judgments in naive subjects were not reliably influenced by reward rate information, but subjects possessing expert knowledge demonstrated judgments that were reliably affected by contingency information. The results indicate that people do not generate generalized knowledge from normal experience with occasional vs. regular reward. Possible explanations and implications of these findings are discussed.     

Method of stimulation, mouth movements, concentration, and viscosity: effects on the degree of taste adaptation

Although sensory adaptation, the gradual loss of sensation during prolonged stimulation, has been demonstrated in laboratory taste experiments, a comparable loss of taste intensity is not experienced in real-life eating situations. This discrepancy may be due to differences in the proximal stimuli or to differences in the ways the taste receptors are stimulated. In two experiments, the effects of four potentially relevant variables were investigated: stimulus intensity, stimulus viscosity, mouth movements, and presentation method. During the initial seconds of stimulation, adaptation to the weakest of the two solutions was faster. Although more viscous stimuli were less sweet, viscosity as such did not affect adaptation rate, nor did mouth movements. Among the three presentation methods, a sucrose-soaked filter paper on the tongue produced more adaptation than either sipping the solution or flowing it over the tongue. This suggests that even mouth movements far more subtle than those still present in the no-movement condition of a sip-and-spit experiment can disrupt the adaptation process.     

Aging and Working Memory Inside and Outside the Focus of Attention: Dissociations of Availability and Accessibility

ABSTRACT

Two experiments used the N-Back task to test for age differences in working memory inside and outside the focus of attention. Manipulations of the difficulty of item-context binding (Experiment 1) and of stimulus feature binding (Experiment 2) were used to create conditions that varied in their demand on working memory, with the expectation that greater demand might increase age differences in focus-switching costs and the search rate outside the focus of attention. Results showed, however, that although age differences were evident in measures of overall speed and accuracy, and the manipulations significantly affected response times and accuracy in the expected direction, the experimental manipulations had no impact on age differences. Findings instead pointed to age-related reductions in accuracy but not speed of focus-switching and search outside the focus of attention. Thus, age-related deficits appear to involve the availability of representations in working memory, but not their accessibility.     

The role of head position and prior contraction in manual aiming

We sought to determine if the asymmetrical tonic neck reflex influences the accuracy of self-selected arm positioning without vision and to ascertain if such accuracy is influenced by a pre-contraction of the prime movers. Participants reproduced an arm position using their abductors with the head in midline, rotated towards and away from the arm. Arm movements were made with and without a pre-contraction of the abductors. Twenty participants performed eight trials in each of the six different conditions. Compared to the midline position, participants undershot the reference position with the head turned away and overshot the position with the head rotated towards the arm. A pre-contraction caused undershooting regardless of head position. Results suggest that head position and pre-contraction may have significant and independent effects on arm positioning.     

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.     

The role of person and object in eliciting early imitation

The role of person and object in eliciting early imitation was examined in this study. Twenty-seven infants, between 5 and 8 weeks old were assigned randomly to two conditions. In the person condition (N = 12) they were presented with tongue protrusions and mouth openings modeled by an adult, whereas in the object condition (N = 15) they were presented with these gestures simulated by two objects. Two infant behaviors were coded; mouth openings and tongue protrusions. Infants in the person condition selectively reproduced the mouth open and tongue protrusion gestures at significant levels, infants in the object condition did not. Instead of reproducing the congruent gestures (mouth openings and tongue protrusions when they were modeled) infants in the object condition reproduced the incongruent gestures at significant levels. Together, the findings indicate that imitation is a social response, which has implications for the development of nonverbal communication and speech.     

How Power States Influence the Persuasiveness of Top‐Dog versus Underdog Appeals

Although both top‐dog and underdog positioning appeals are widely used in marketing and advertising, little is known about which strategy is more effective in persuading consumers. By introducing a sense of power, a social variable that is inherently relevant to the nature of the top‐dog versus underdog classification, we propose that consumers' responses to these two appeals are influenced by their psychological experience of power. Specifically, low‐power consumers will respond to top‐dog appeals more favorably because associating with top dogs facilitates power restoration. In contrast, high‐power consumers will respond to underdog appeals more favorably because supporting underdogs facilitates power expression. In four experimental studies, we provide consistent support for our main predictions as well as the underlying processes. Studies 1 and 2 demonstrate the differential effect of consumers' power states on their attitudes toward top‐dog versus underdog appeals. Providing process evidence, Studies 3 and 4 identify boundary conditions under which the basic effect was eliminated. These findings contribute to the persuasion literature and power research and provide important implications for positioning strategy and advertisement development.     

Internal versus external references with respect to perception of stimuli on the body surface

Previous studies on the determinants of locus of perception of stimuli on the body have suggested that the position of the stimulus has a significant effect whether a subject perceives a tactile pattern as seen from inside or outside the body. However, it is possible that previous investigators confounded stimulus location--dorsal or frontal--and experimenter's position--behind or in front of the subject. Using 42 male subjects in a 2 X 2 design, the effects of experimenter's position and stimulus location were studied by a new technique for inferring locus of perception. Experimenter's position, rather than stimulus location, affects subjects' locus of perception. Perception of stimuli on the body involves three independent factors, the demand characteristics of the experiment, the manner in which an individual perceives the boundaries of his own body, and an individual's ability to adopt the experimenter's perceptual standpoint.     

How toddlers represent enclosed spaces

Recent findings indicate that toddlers can use geometric cues to locate an object hidden in a corner of a rectangular room after being disoriented [Cognition 61 (1996) 195]. It has been suggested that locating the object involves reestablishing one's initial heading. The present experiments examine search behavior after disorientation. We find that toddlers go directly to a particular corner, indicating that they do not have to reestablish their original heading. It also has been suggested that toddlers ability to use geometric cues is limited to surrounding spaces. We find that toddlers can locate an object from outside as well as from inside a space, although the task is harder from outside. Based on these results, we argue that while toddlers do not represent their position relative to a particular portion of a space, they nevertheless may represent their position relative to the entire space (i.e., outside vs. inside).     

Vision and proprioception in simple catching

Articular proprioception is normally considered to provide accurate information about limb position, particularly in ball skills in which the eyes are be occupied with tracking the ball. If this is so, then preventing sight of the catching hand without interfering with visual tracking of the ball should affect the accuracy of catching. The experiment reported here indicates that is not the case. Catching is much less accurate if the hand cannot be seen. The errors made are in positioning of the catching hand, which frequently does not contact the ball. In addition, subjects showed larger changes in the felt length arms after catching without sight of the hand than did those who could hand while catching. Visual information about the position of the hand for catching, and this may be because the proprioceptive system is by vision.     

Perioral somatosensory determinants of nursing behavior in Norway rats (Rattus norvegicus)

Prior to assuming the upright crouching posture over their pups during nursing bouts, lactating rats typically engage in several oral behaviors, including nuzzling, licking and rearranging pups. By acutely depriving dams of various aspects of perioral stimulation from pups (with anesthesia of the mystacial pads or of the tongue, with mouth suturing, or with muzzling), we found the following: (1) Distal stimulation from pups maintains proximity-seeking behavior, but is insufficient to stimulate nursing behavior. (2) Lack of tongue feedback decreases pup licking and hastens the onset of crouching. (3) Snout, but not tongue, contact with pups is required for hovering over them. (4) The position of the dam while hovering over her litter enables the pups to gain access to her ventrum, thereby provoking her upright, crouching posture. (5) Older pups are capable of bypassing the dam's perioral attentions and stimulating crouching directly by burrowing under the dam's ventrum.     

Evaluating scientific research: Belief,hindsight bias,ethics, and research evaluation

Students may exhibit two forms of cognitive biases, belief and hindsight bias, in evaluating a scientific experiment. Counter to disagreement, they may only believe an outcome that agrees with their belief to be more predictable in hindsight than foresight. The focus of this research is on the relationship between these biases. Students were queried about their dichotomous beliefs (learned vs. genetic) about behavior for an animal experiment and then assigned randomly to a no‐outcome or genetic outcome condition. With agreement between students' belief and outcome, the findings revealed hindsight bias (foreseeability) supported by the outcomes for surprise, disappointment, ethics, and research evaluation. With disagreement, hindsight bias was trumped along with perceiving the experiment as being less ethical and scientifically sound. Regardless of the outcome, students seem to adhere to their beliefs. Hence, students may believe that the outcome is inconsequential because it is obvious or contrary to their beliefs.     

Adaptation to visual and proprioceptive rearrangement: Origin of the differential effectiveness of active and passive movements

In Experiment 1, subjects exposed to a discordance between the visual and ”proprioceptive” locations of external targets were found to exhibit aftereffects when later pointing without sight of their hands at visual targets. Aftereffects occur both when the discordance is introduced in the traditional fashion by displacing the visual locations of targets and when the proprioceptive locations of targets are displaced. These observations indicate that there is nothing unique about the visual rearrangement paradigm—the crucial factor determining whether adaptation will be elicited is the presence of a discordance in the positional information being conveyed over two different sensory modalities. In a second experiment, the effectiveness of active and passive movements in eliciting adaptation was studied using an experimental paradigm in which subjects were exposed to a systematic discordance between the visual and proprioceptive locations of external targets without ever being permitted sight of their hands; a superiority of active movements was observed, just as is usually found in visual rearrangement experiments in which sight of the hand is permitted. Evidence is presented that the failure of passive movements to elicit adaptation is related to a deterioration in accuracy of position sense information during passive limb movement.