Limitations of a Bidirectional Control Procedure for the Investigation of Imitation in Rats: Odour Cues on the Manipulandum

Magazine-trained observer rats confronted a conspecific demonstrator pushing a joystick to the right or to the left for food reward before the observers were given access to the joystick from the position previously occupied by the demonstrator and rewarded for responses in both directions. For half of the observers (group 0), the joystick was in the same position when acted upon by demonstrators and observers; for the other half (group 180) the manipulandum was rotated 180 within its mounting between observation and test. As in previous experiments using this bidirectional control procedure, rats in group 0 showed demonstratorconsistent responding-that is, they pushed the joystick in the same direction, relative to the actor's body, as had their demonstrators. However, group 180 showed a reverse effect: reliable demonstrator-inconsistent responding. These results suggest that attractive odour or taste cues deposited by demonstrators on the side of the joystick contralateral to the direction of responding are sufficient to produce demonstrator-consistent responding in the bidirectional control procedure.     

Joystick acquisition in tufted capuchins (<Emphasis Type="Italic">Cebus apella</Emphasis>)

A number of nonhuman primate species have demonstrated the ability to use a joystick to control a cursor on a computer screen, yet the acquisition of this skill has not been the focus of systematic inquiry. Here, we examined joystick acquisition in four tufted capuchins under two directional relationships of joystick movement and resultant cursor displacement, isomorphic and inverted. To document the natural history of the acquisition of this skill, we recorded the development of visual tracking of the cursor and body tilting. Rates of acquisition were comparable between the two conditions. After mastering the task in one condition, subjects remastered the task at an accelerated rate in the opposing condition. All subjects significantly increased or maintained high proportions of cursor tracking throughout acquisition. All subjects demonstrated a postural tilt while moving the cursor from the mid-phase of acquisition through task mastery. In the isomorphic condition, all subjects tilted significantly more often in the direction of goal location than in the opposite direction. In three of the four series of tilting that were scored for subjects in the inverted condition, tilting occurred significantly more often toward the direction of goal location than the direction of required hand movement. Together these findings suggest that body tilting participates in the organization of directional movement of the cursor rather than reflecting merely the motoric requirements of the task (to manipulate a joystick).     

A demonstration of observational learning in rats using a bidirectional control

Hungry rats observed a conspecific demonstrator pushing a single manipulandum, a joystick, to the right or to the left for food reward and were then allowed access to the joystick from a different orientation. The effects of right-pushing vs left-pushing observation experience on (1) response acquisition, (2) reversal of a left-right discrimination, and (3) responding in extinction, were examined. Rats that had observed left-pushing made more left responses during acquisition than rats that had observed right-pushing, and rats that had observed demonstrators pushing in the direction that had previously been reinforced took longer to reach criterion reversal and made more responses in extinction than rats that had observed demonstrators pushing in the opposite direction to that previously reinforced. These results provide evidence that rats are capable of learning a response, or a response-reinforcer contingency, through conspecific observation.     

Imitation in rats: Initial responding and transfer evidence

In two experiments, rats observed a conspecific demonstrator pushing a single manipulandum, a joystick, to the right or to the left for food reward before being given access to the joystick, for the first time, from a different orientation. In Experiment 1, rats that had observed left-pushing made more of their first three responses to the left than did rats that had observed right-pushing. In Experiment 2 the axis of joystick movement was rotated through 90° between observation and testing for half of the animals. These rats, like those that were tested with the joystick in the position it had occupied during demonstrator responding, showed a significant tendency to push the joystick in the same direction relative to their own bodies as had their demonstrators. These results, which cannot be explained in terms of stimulus-reinforcer learning, provide evidence that rats are capable of imitation, i.e. response, or response-reinforcer, learning by observation.     

A new breed of computer users: rats control a cursor via joystick manipulation.

Many exciting findings have been reported in the 15 years since monkeys were first demonstrated to have the capacity to perform computerized tasks. The present data indicate that albino rats can also learn to respond to computer-generated stimuli by manipulating a joystick. Although the rat's control of the cursor is not as skillful as has been reported for primate species, it is clearly better than chance and suggests the great potential for comparative investigation afforded by use of the computer test system.     

Seeing how it’s done: matching conditions for observer rats (Rattus norvegicus) in the bidirectional control

In an attempt to increase the reliability of the demonstrator-consistent responding effect produced in the bidirectional control procedure, experiments 1–4 sought conditions that would magnify the matching effect. The aim was to produce a robust demonstrator-consistent responding effect in order that future analytic experiments could investigate the psychological processes responsible for this effect. The joystick responses of observer rats trained using the standard bidirectional control procedure parameters were compared with those of observers subject to conditions identified in the social learning literature as favourable for imitation. Unlike mice, observer rats in experiments 1 a and 1 b tended to push a joystick in the same direction as their demonstrators when the demonstrators were either familiar or unfamiliar males and females. Comparable demonstrator-consistent responding occurred following observation of a standard and a salient joystick response (experiment 2). Experiment 3 showed that the discriminative accuracy of a demonstrator’s responding was important for matching behaviour, and suggested that matching might be enhanced with more than the conventional single observation session. Experiment 4 confirmed that the bidirectional control effect is sensitive to the amount of observational experience; after six observation sessions, demonstrator-inconsistent responding occurs. The results of experiments 1–3 are, and those of experiment 4 are not, compatible with the hypothesis that demonstrator-consistent responding in the bidirectional control is caused by olfactory cues deposited by demonstrators on the joystick. Received: 29 May 2000 / Accepted after revision: 28 August 2000     

A new breed of computer users: Rats control a cursor via joystick manipulation

Many exciting findings have been reported in the 15 years since monkeys were first demonstrated to have the capacity to perform computerized tasks. The present data indicate that albino rats can also learn to respond to computer-generated stimuli by manipulating a joystick. Although the rat’s control of the cursor is not as skillful as has been reported for primate species, it is clearly better than chance and suggests the great potential for comparative investigation afforded by use of the computer test system.     

Motor imagery effectiveness for mirror reversed movements

Physical practice is known to enhance motor adaptation skills, which refer to the individual ability to compensate for environmental changes. So far, it is still unknown whether a similar effect can be observed following motor imagery (MI). Thirty-nine participants were tested during a joystick tracking task under both normal and mirror conditions (i.e., the inductive direction of the joystick was reversed), before and after a physical practice or MI training phase. Eye movements and electromyographic activity were recorded during MI. Motor performance was also evaluated after a 6 h interval during daytime. As compared to the control group, the results revealed that both MI and physical practice improved motor performance in the mirror condition, during the post-training test. Furthermore, the time to complete the task was further reduced after 6 hours, both in the normal and mirror conditions. These results demonstrate the effectiveness of MI for learning mirror-reversed movements, and for the consolidation process that follows motor adaptation.     

Influence of body-centered information on the transfer of spatial learning from a virtual to a real environment

This study investigated the effects of body-centred information on the transfer of spatial learning using a wayfinding task and tasks that specifically probe the route and survey strategies of navigation. The subject learned a route in either a real or a virtual environment (VE; 3D scale model of a Bordeaux neighbourhood) and then reproduced it in the real environment. The involvement of body-based information was manipulated across the spatial learning conditions in the VE: participants learned with full body-based information (treadmill with rotation), with the translational component only (treadmill without rotation) or without body-based information (joystick). In the wayfinding task, the results showed a significant effect of the learning environment with the best scores obtained in the real and treadmill with rotation conditions. There was no significant difference between these two conditions, but the real condition was significantly different from the treadmill without rotation and joystick conditions. Also, the visual flow was sufficient to successfully perform the two egocentric tasks used as well as a direction estimation task (a survey task), in so far as there is no significant difference between the joystick and the treadmill conditions. By contrast, the distance estimates were improved by the treadmill condition including the translational component (but not the rotational component). Finally, our results show that treadmill with rotation promotes the transfer of spatial learning from a virtual to a real environment (compared to joystick and treadmill without rotation). Moreover, body-centred informations are more involved in allocentric (distance estimates) than egocentric navigational strategies.     

Effects of directional uncertainty on visually-guided joystick pointing

Reaction times generally follow the predictions of Hick's law as stimulus-response uncertainty increases, although notable exceptions include the oculomotor system. Saccadic and smooth pursuit eye movement reaction times are independent of stimulus-response uncertainty. Previous research showed that joystick pointing to targets, a motor analog of saccadic eye movements, is only modestly affected by increased stimulus-response uncertainty; however, a no-uncertainty condition (simple reaction time to 1 possible target) was not included. Here, we re-evaluate manual joystick pointing including a no-uncertainty condition. Analysis indicated simple joystick pointing reaction times were significantly faster than choice reaction times. Choice reaction times (2, 4, or 8 possible target locations) only slightly increased as the number of possible targets increased. These data suggest that, as with joystick tracking (a motor analog of smooth pursuit eye movements), joystick pointing is more closely approximated by a simple/choice step function than the log function predicted by Hick's law.     

Processing deceptive information in sports: Individual differences for responding to head fakes depends on the attentional capability of the observer

In team sports, players sometimes try to deceive their opponents by providing misleading information in order to gain a temporal advantage. Head-fakes are often applied when a player gazes in one direction, while passing/shooting the ball in another direction. The opponent is challenged to focus attention on the relevant information (i.e., pass direction), while ignoring the conflicting information (i.e., gaze direction). The present study aimed to identify the link between attentional capabilities and the effectiveness of head fakes. Twenty-seven novices performed in a basketball-specific head-fake task and in the attention-window task. A correlation between performances in both tasks revealed that participants with higher attentional capabilities were better able to focus their attention on the relevant feature (pass direction), when judging basketball situations, than participants with lower attentional capabilities. The results emphasize the relevance of high attentional capabilities in team sports and indicate that focusing one’s attention to the pass direction poses a possibility of reducing the effects of head fakes.     

Multi-scale control influences sense of agency: Investigating intentional binding using event-control approach

Control exercised by humans through interactions with the environment is critical for sense of agency. Here, we investigate how control at multiple levels influence implicit sense of agency measured using intentional binding. Participants are asked to hit a moving target using a joystick with noisy control followed by an intentional binding task initiated by the target hitting action. Perceptual-motor level control was manipulated through noise in the joystick controller (experiment 1) and goal-level control in terms of feedback about successful hit (experiments 2a and 2b). In the first experiment, intentional binding increased with amount of joystick control only when goal was not achieved and independent otherwise suggesting that the two levels interact hierarchically. In the second experiment, the estimated duration was dependent on when participants knew about goal completion. The results are similar to those obtained with explicit measures of sense of agency indicating that multi-scale event control influences agency.     

Systematic evaluation of current control devices used by people with intellectual disabilities in non-immersive virtual environments.

Virtual environments have a role to play in facilitating the acquisition of living skills in people with intellectual disabilities, improving their cognitive skills and providing them with entertainment. However, the currently recommended devices to allow navigation in and interaction with the environments are difficult to use. Using a methodology established in an earlier study, the study aims to systematically document the performance of users with the currently recommended devices in order to (i) inform the design of a usable control device or devices and (ii) act as a baseline against which they can be evaluated. 40 people with severe intellectual disabilities aged 21-67 years used four environments with an equal number of sessions with the different devices being evaluated. Results indicate that when forward movement is provided by the software using the mouse for both navigation and interaction allows better performance both initially and after exposure than using the fire button on the joystick. When the user had to initiate forward movement with the navigation device, the joystick allowed better performance than the arrows on the keyboard. Preventing slippage of the joystick base would make its use much easier and it is suggested that separate devices are retained for navigation and interaction.     

Evidence for internal representation of a static nonlinearity in a visual tracking task

A group of 24 participants was given over 3 h practice at a visual pursuit tracking task with a pronounced static nonlinearity between movement of the joystick and the resulting deflection of the response cursor. The aim was twofold: (1) to determine whether or not participants compensated for the nonlinearity and (2) to show that any such compensation involved the formation of an internal representation of the nonlinear relationship between movement of the joystick as sensed kinaesthetically and/or visually and movement of the response cursor as sensed visually. Results show that participants introduce partial compensation for the static nonlinearity. Furthermore, partial compensation was present even during open-loop tracking when participants were deprived of visual feedback of the position of the response cursor. This implies that participants are able to form an internal representation of the nonlinear relationship between movement of the joystick and the resulting movement of the response cursor.     

Miller (1944) revisited: Movement times in relation to approach and avoidance conflicts

Three experiments (total N = 291) sought to provide support for the idea that avoidance conflicts, relative to approach conflicts, are more difficult to motorically resolve. Conflicts were instantiated by asking individuals to approach desirable stimuli and avoid undesirable stimuli under conditions in which there was no objectively-correct direction of movement. To control for baseline movement speeds, non-conflict trials presented desirable (e.g., reward) and undesirable (e.g., threat) stimuli in the absence of any spatial conflict. In addition, movement times were isolated through the use of a joystick movement paradigm in which movement speeds were quantified subsequent to some initial tendency to move in one direction or the other. Consistent with hypotheses, all experiments found that movement times were slowed in the context of avoidance conflicts relative to approach conflicts. Results are discussed in terms of theories of motivation, affective processing, conflict, and anxiety.     

Revised Space Fortress: A validation study

We describe briefly the redevelopment of Space Fortress (SF), a research tool widely used to study training of complex tasks involving both cognitive and motor skills, to be executed on currentgeneration systems with significantly extended capabilities, and then compare the performance of human participants on an original PC version of Space Fortress (SF) with the revised Space Fortress (RSF). Participants trained on SF or RSF for 10 sets of eight 3-min practice trials and two 3-min test trials. They then took tests involving retention, resistance to secondary task interference, and transfer to a different control system. They then switched from SF to RSF or from RSF to SF for 2 sets of final tests and completed rating scales comparing RSF and SF. Slight differences were predicted on the basis of a scoring error in the original version of SF used and on slightly more precise joystick control in RSF. The predictions were supported. The SF group started better but did worse when they transferred to RSF. Despite the disadvantage of having to be cautious in generalizing from RSF to SF, we conclude that RSF has many advantages, which include accommodating new PC hardware and new training techniques. A monograph that presents the methodology used in creating RSF, details on its performance and validation, and directions on how to download free copies of the system may be downloaded from www .psychonomic.org/archive/.     

Fitts' Law in two dimensions with hand and head movements

Subjects performed two-dimensional discrete movements either with a helmet-mounted sight or with a joystick. Fitts' Law was found to be a good predictor of the speed-accuracy tradeoff for both systems. The joystick produced faster movement times than the helmet-mounted sight. For both systems, horizontal and vertical movements were slightly faster than diagonal movements. Two dimensional generalizations of Fitts' Law were discussed in terms of multidimensional scaling. The obtained pattern of movement times was found to be intermediate to the predictions of Euclidean and City-block models of the movement space. Muscle coordination strategies were considered, and a strictly serial coordination model was rejected. A strictly parallel model was also rejected for the helmet-mounted sight, but not for the joystick.     

Adult age differences in inhibitory processes and their predictive validity for fluid intelligence

According to the inhibition-deficit hypothesis age differences in working memory capacity and fluid intelligence have been attributed to a decline in inhibitory efficiency. Conceptualizing inhibition as multifaceted, 88 participants (49 younger and 39 elderly) completed two versions of the negative priming paradigm (identification and localization), and two variants of the directed forgetting paradigm (listwise and itemwise). Two tasks of the Wechsler Intelligence Test with high loadings on general fluid intelligence (Gf) served as validation criteria. Results revealed task-specific and speed-independent inhibitory deficits in the elderly (lower negative priming in both paradigms; more intrusions in the directed forgetting tasks), as well as higher levels of repetition priming. Significant correlations between measures of inhibition and the Wechsler scores were found in both age groups. Results support the view of multiple inhibitory-like capabilities that play a central role in the decline of higher-order cognitive functions in old age.     

The sensory basis of target location

Overshoot rate in a target alignment task depends on the location of the target with reference to the operational boundary of the task. Subjects performed a step tracking task under four conditions combining pursuit and compensatory display modes with joystick and crank control devices. The boundary effect was found when the joystick was used but not the crank, while the display mode had no effect, indicating that subjects moved with respect to a frame of reference based on proprioceptive information. Movements were made according to the postures adopted, irrespective of the concomitant visual consequences.     

Commanding the direction of passive whole-body rotations facilitates egocentric spatial updating

In conditions of slow passive transport without vision, even tenuous inertial signals from semi-circular canals and the haptic-kinaesthetic system should provide information about changes relative to the environment provided that it is possible to command the direction of the body's movements voluntarily. Without such control, spatial updating should be impaired because incoming signals cannot be compared to the expected sensory consequences provided by voluntary command. Participants were seated in a rotative robot (Robuter) and learnt the positions of five objects in their surroundings. They were then blindfolded and assigned either to the active group (n=7) or to the passive group (n=7). Members of the active group used a joystick to control the direction of rotation of the robot. The acceleration (25 degrees /s2) and plateau velocity (9 degrees /s) were kept constant. The participants of the passive group experienced the same stimuli passively. After the rotations, the participants had to point to the objects whilst blindfolded. Participants in the active group significantly outperformed the participants in the passive group. Thus, even tenuous inertial cues are useful for spatial updating in the absence of vision, provided that such signals are integrated as feedback associated with intended motor command.