Effects of serotonin-mimetic drugs on mouse-killing behavior

Muricidal behavior induced in rats by social isolation or by olfactory bulb ablation was blocked following IP administration of serotonin (5–HT) agonist 8-OH-DPAT and 5-MeODM and by 5-HT uptake inhibitors, fluoxetine and indalpine. Among uptake inhibitors, although fluoxetine has a higher IC₅₀ and a higher Ki, it is apparently more efficient than indalpine. The 5-HT agonist, 8-OH-DPAT, acting at a putative 5-HT_1A receptor, appears more efficient on muricidal inhibition than 5-MeODM, at a much lower dosage. It is highly probable that 5-HT_1A receptor rather than 5-HT_1B is involved in the antimuricidal effect of serotonin-mimetic drugs. Since 5-HT mimetic drugs blocked mouse-killing behavior of bulbectomized rats, we suggest that in the sequence of events in muricidal inhibition 5-HT circuits participate after gabaergic modulation from olfactory bulbs.     

Biting attack by rats in response to aversive shock

Paired rats are known to behave aggressively when given painful electric shocks. The present study developed a procedure whereby individual rats given shocks might bite an inanimate target object. Unavoidable shock was delivered to the rat while it was restrained in a position close to, and facing a target object. Biting of the target was recorded automatically. Shock caused the rat to bite metal, wood, or rubber targets. Biting was most frequent immediately after shock and decreased as a direct function of time since the shock. Almost every shock produced biting and the behavior continued as long as the shocks were delivered. Biting ceased within and between sessions when shocks were discontinued. These results show how the pain-aggression relation can be studied objectively with rats.     

Children's autokinetic movement as a function of inferred movement of target shape

Four target shapes, a control stimulus (circle) and one each representing geometrical (arrow), representational (car), and symbolic (cross) implied movement were presented to 10 children in each of five age groups of boys and girls (4, 6, 8, 10, 12 yr.) in an autokinetic movement task. While there were no differences in direction of perceived movement with regard to the control stimulus (circle), all other target shapes showed a decrease in the effects of implied movement with increases in age. The minor sex differences were not reported.     

The effect of movement amplitude and target diameter on reaction time

Henry's (Henry & Rogers, 1960) memory drum model of neuromotor reaction, which predicts an increased response latency for more complicated movements, was tested by examining the effects of variations in movement amplitude and target diameter on choice RT. RT tended to increase with decreasing target diameter, and varied as a U-shaped function with amplitude. Such findings were in only partial support of the memory of drum notion. The data were discussed in relation to information processing, muscle activation, and subjects' expectations for executing responses along the range of movement amplitude.     

The movement of the hand towards a target

Previous work on the approach trajectories of hands to targets in tracking and aiming tasks had produced contradictory evidence about the shape of these curves. This paper shows that these trajectories are a function of the level of practice of the subject; an interpretation in terms of the theory of intermittent control of movements is advanced. Previous contradictory data can be resolved by reference to the subjects/ level of practice. In addition, this theory will encompass the differences between accurate and free movement trajectories reported earlier.     

Pictorial target control of schedule-induced attack in White Carneaux pigeons

Three pigeons with a history of attacking a mirror target, and two of six pigeons with no prior exposure to targets, attacked a colored photograph of a conspecific during exposure to intermittent schedules of reinforcement for key pecking. Rate of attack on the photograph decreased when the reinforcement schedule was removed. The topography, temporal pattern, and locus of attack on the picture were comparable to schedule-induced attack on live, stuffed, and mirror targets. When silhouette, outline, and plain paper targets were used, schedule-induced attack was more sensitive to a change in target characteristics with a concurrent target-preference procedure than with an analogous successive-testing procedure. The combined results of the two testing procedures indicated that an “upright” white-on-black silhouette of a pigeon with or without an eye was more effective in controlling attack than was a comparable “inverted” silhouette, an outline of a pigeon, or a piece of colored paper.     

Effects of attack and uncontrollable noise on aggression

After being either attacked or treated in a more neutral manner by an experimental confederate, male subjects shocked the confederate while being stimulated by loud noise. Among previously attacked subjects, possession of control over offset of the noise led to the delivery of shocks significantly shorter in duration than those given by subjects who did not have control. Mere predictability of noise offset did not have the same effect. Subjects who could control the noise did not differ from those who heard no noise with respect to the duration of shocks given. Noise had no effect on shock duration among nonattacked subjects. In a follow-up study subjects who were given bogus information that they were aroused by noise were less punitive toward an attacking confederate than subjects given no such information. The overall conclusion is that noise facilitates aggression in subjects who have been instigated to aggress to the degree that noise-produced arousal is misattributed to the instigating stimulus.     

Effects of smoking abstinence on movement regulation

The effect of smoking abstinence on performance of a reciprocal tapping task was investigated. 6 habitual smokers performed a single-plate and two versions of a two-plate tapping task. Fitts' Law was used to compute an index of difficulty (ID) in bits for the tasks which was 0 bits for the single-plate and 3.32 and 4.17 bits for the two-plate versions of the task. While smoking abstinence had no effect on performance of the single-plate tapping task, it increased movement time on performance of both two-plate task versions. These findings may provide a coherent explanation for the prior findings of nicotine deprivation on psychomotor performance in the literature. This explanation suggests that the effects of nicotine deprivation as incurred through smoking abstinence may be on the central mechanisms regulating information-processing rate for successful movement regulation. Thus nicotine deprivation may not affect performance of simple psychomotor tasks which require minimal information processing but will affect the performance of more complex tasks requiring significantly more information processing for successful movement regulation.     

Effects of attentional-focus instructions on movement kinematics

BackgroundRecent research has shown that internal (body-related) attention-focus instructions disrupt motor learning and performance, whereas paying attention to the environmental effects of movements (external focus) leads to better performance than an internal focus [see, for reviews, Wulf, G. (2007). Attentional focus and motor learning: a review of 10 years of research. E-Journal Bewegung und Training, 1, 4–14.; Wulf, G., &; Prinz, W. (2001). Directing attention to movement effects enhances learning: a review. Psychonomic Bulletin &; Review, 8, 648–660.]. However, Beilock's studies [Beilock, S. L., Bertenthal, B. I., McCoy, A. M., &; Carr, T. H. (2004). Haste does not always make waste: expertise, direction of attention, and speed versus accuracy in performing sensorimotor skills. Psychonomic Bulletin &; Review, 11, 373–379.] suggest that an internal focus is detrimental in experts but not in novices. Because detrimental effects of consciously attending to movements have generally been measured by performance scores such as accuracy scores or reaction times, it remains unclear how internal and external attentional-focus instructions influence movement kinematics when learning a new skill. To fill this gap, the present study investigated attentional-focus effects on a biomechanical level.MethodsA video of an expert juggler demonstrating a two-ball juggling task was presented to juggling novices. Experimental groups were given either body-related (internal group) or ball-related (external group) verbal instructions or no attention-guiding instructions (control group). In the retention phase without attention-guiding instructions, the body-movement and ball-flight aspects of performance focused on in the verbal instruction were subjected to biomechanical analyses.Results and ConclusionsJuggling performance improved equally in all three groups. However, internally vs. externally instructed acquisition phases had differential effects on the kinematics of the upper body as well as ball trajectories when performing the juggling task. Remarkably, ball trajectories in the control group who received no specific attentional cueing were similar to those in the externally instructed group. This suggests that task-relevant information is picked up independently of instructions, and that external instructions provide redundant information. Internal instructions for object-related tasks, however, may confront novice learners with the need to process additional information. As a result, task difficulty might be unnecessarily enhanced in an observational learning setting.     

Effects of shock intensity and duration on the frequency of biting attack by squirrel monkeys

Squirrel monkeys were periodically exposed to brief tail-shocks in the presence of a rubber tube connected to a pneumatic switch. Biting attack upon this tube was found to be a decreasing function of time since shock delivery and a direct function of shock intensity and duration. These results parallel findings in investigations employing more “naturalistic” social situations, indicating that attack against the inanimate and animate environment is a direct function of the intensity of an aversive stimulus. The results also demonstrate that frequency of biting attack as a datum is sensitive to several experimental manipulations.     

Advanced information about target location facilitates movement planning: More evidence using a deadline procedure on movement time

It was recently shown that in a multiple choice aiming task the knowledge of the target location prior to stimulus introduction, even though the trajectory to follow was still uncertain, facilitated movement planning and execution (Girouard et al. 1987). In that particular study, the subjects had, in the first condition, knowledge about the target location prior to the stimulus presentation. In that condition, they started their movements in the direction indicated by one of four possible stimuli. However, they always ended their movements on the same target (single-target condition). In a second condition, there was always a one-to-one mapping between the stimuli and the targets (multiple-target condition). The facilitating effects of knowing target location were found for both the movement planning time or reaction time (RT) and movement time (MT). A possible explanation of the latter effect was that the subjects, somewhere along the movement path, made a check to see if their movement was carried out as expected and corrected it accordingly. The purpose of the present experiment was to see if knowing the target to reach before the stimulus presentation, even though the trajectory to follow is uncertain, could override the well-known effect of stimulus-response uncertainty on RT (Hick 1952) when the possibility of making a check during MT was reduced. To reach that goal the methodology used by Girouard et al. (1987) was modified by limiting the time permitted to execute the required response. The effect of this manipulation was that it almost tripled the target location effect on RT found in the previous study. Furthermore, the significant effect found on MT disappeared for the single-target condition whilst it remained significant for the multiple-target condition. Different interpretations are offered to take into account the latter result.     

Grasping a 2D virtual target: The influence of target position and movement on gaze and digit placement

While much has been learned about the visual pursuit and motor strategies used to intercept a moving object, less research has focused on the coordination of gaze and digit placement when grasping moving stimuli. Participants grasped 2D computer generated square targets that either encouraged placement of the index finger and thumb along the horizontal midline (Control targets) or had narrow “notches” in the top and bottom surfaces of the target, intended to discourage digit placement near the midline (Experimental targets). In Experiment 1, targets remained stationary at the left, middle, or right side of the screen. Gaze and digit placement were biased toward the closest side of non-central targets, and toward the midline of center targets. These locations were shifted rightward when grasping Experimental targets, suggesting participants prioritized visibility of the target. In Experiment 2, participants grasped horizontally translating targets at early, middle, or late stages of travel. Average gaze and digit placement were consistently positioned behind the moving target's horizontal midline when grasping. Gaze was directed farther behind the midline of Experimental targets, suggesting the absence of a flat central grasp location pulled participants' gaze toward the trailing edge. Participants placed their digits at positions closer to the horizontal midline of leftward moving targets, suggesting participants were compensating for the added mechanical constraints associated with grasping targets moving in a direction contralateral to the grasping hand. These results suggest participants minimize the effort associated with reaching to non-central targets by grasping the nearest side when the target is stationary, but grasp the trailing side of moving targets, even if this means placing the digits at locations on the far side of the target, potentially limiting visibility of the target.     

Effects of novel odors on intermale attack behavior in mice

Offensive, defensive, and nonagonistic social behaviors of resident male mice toward unfamiliar intruders were examined during exposure to the novel odors of chocolate or sheep's wool. Both novel odors reduced lateral attacks and boxing when compared to familiar sawdust odor. Chocolate, but not sheep's wool, also reliably increased flight behavior by residents. Neither social behaviors nor self-grooming were affected by these odors. The novel odors had no effect upon, or actually decreased, the defensive responses of intruders towards residents. The equivalent effectiveness of both predator and nonpredator odors in elevating risk assessment and suppressing attack during firsttime exposure, and the decreased potency of cat odors following repeated exposure, suggests that novelty contributes to the enhanced defensiveness seen among subjects during initial exposure to predator odors. © 1995 Wiley-Liss, Inc.     

Effects of attentional focus on movement coordination complexity

Attentional focus affects performance and learning of motor tasks. An external attentional focus (on the effects of movement) can lead to more efficient and effective movements compared to an internal focus (on body movement itself). According to the “constrained action hypothesis”, an external focus facilitates fast and reflexive movement control while an internal focus leads to disruption of automatic coordination processes. Such disruption should be apparent in the complexity of movement. In this study, multiscale entropy measures were used to investigate if the external focus is related to superior coordination complexity compared to internal focus. Twenty participants were divided in two groups that balanced over an unstable platform in fourteen trials over two days, either with internal or external focus of attention instructions, followed by seven retention trials on the third day. Multiscale entropy measures were used to quantify complexity of motions of the platform, the participant, and the composite of participant and platform motions. Results were contrary to expectations. For the external focus group, despite better overall performance, multiscale entropy values of participant and composite motions were lower in some scales compared to the internal focus group, especially in the first and last days. This may be consistent with previous findings that predictability increases during learning of a balance task. Results also indicate the need to identify the correct physiological interpretation of single or multiscale entropy measures. Further investigation is needed to establish if entropy differences are causally related to performance and learning advantages of the external focus.     

Effects of noise and attack on aggression and physiological arousal

Sixty male subjects were first given either 10 shocks or 2 shocks by an experimental confederate. Two-thirds were then stimulated with loud and aversive noise while the other one-third were not so stimulated. In one of the noise-stimulated conditions, the subject was free to terminate the noise. In the other condition, the subject had no control over the noise. Subjects in all conditions were then given an opportunity to aggress against the confederate. Measures of skin conductance, pulse rate, and blood pressure were made after the subject had been shocked and again after the noise had been given. Subjects who had been given 10 shocks followed by uncontrollable noise gave shocks of longer duration than subjects in any other condition. Subjects given uncontrollable noise also showed evidence of being more physiologically aroused than those given controllable noise or no noise.This research was supported by Grant GS 40171 from the National Science Foundation to the first author.