The influence of cue type and configuration upon radial-maze performance in the rat

The influence of cue type and cue configuration on radial-maze performance in rats was examined in two experiments. In the first experiment, it was found that rats provided with both salient intramaze and extramaze cues acquired the task faster than rats given only one set of cues. No difference in acquisition was found between a group trained with intramaze cues alone and a group trained with extramaze cues alone. In a cue-preference test, it was found that groups that had been trained with extramaze cues, intramaze cues, or both sets of cues relied on extra-maze cues to avoid visited arms when given both types of cues concurrently. When all groups were transferred to intramaze-cue-alone trials, only the group that had been originally trained with extramaze cues alone showed any disruption. Also, during the second half of the intramaze-cue-alone trials, the arrangement of these cues was randomly changed on each trial. This disruption in cue configuration did not deleteriously affect performance in any of the three groups; all remained above chance performance, although the performance of the group originally trained with extramaze cues alone was inferior to that of the other two groups. In Experiment 2, groups of rats were trained on daily alternating trials under intramaze-cue-alone and extramaze-cue-alone conditions. For one group, the configuration of intramaze cues was altered randomly on each trial; the other group had intramaze cues always presented in the same configuration over trials. It was found that acquisition was more rapid on intramaze trials in the group given static configurations. Also, acquisition of the extramaze task was faster than the intramaze task in the group given variable intramaze cue configurations. No difference was found between the intramaze and extramaze conditions in the group given static intramaze cue configurations. These data suggest that a static cue configuration may influence radial maze performance, but is not a necessary condition for such performance.     

Intramaze cues and “odor trails” fail to direct choice behavior on an elevated maze

The relative importance of intramaze cues and extramaze cues in directing choice behavior on a radial arm maze was examined using a discrimination procedure which selectively rewarded rats for following only one set of cues. Rats in the intramaze group obtained food from a food cup on the end of each arm. Rats in the extramaze group obtained food from a food cup on a small platform just beyond the end of each arm. All rats were first shaped to perform correctly with the maze in a constant position. Then the maze was rotated to a new position after every choice. For rats in the intramaze group, the food moved with the arms, making intramaze cues relevant. For rats in the extramaze group, the food remained on the platforms (in the same position in the room), making extramaze cues relevant. Rats in the extramaze group performed almost perfectly during maze rotation, demonstrating that intramaze cues were not necessary to support accurate choice behavior. Rats in the intramaze group never performed better than chance, demonstrating that intramaze cues (from the rats, the reinforcement, and the apparatus) were not adequate to control choice behavior. The results of the present experiment are compared to those of other experiments describing the influence of “odor trails” or other olfactory stimuli on choice behavior in mazes.     

Repeated failures in reducing rat’s spontaneous alternation through the intertrial disruption of spatial orientation

Three experiments examined the contention that an extramaze cue representing relative spatial direction controls rats’ spontaneous alternation. Attempts to eliminate this short-term directional memory by horizontally rotating the Ss were without effect. These data, along with other recent findings, cast doubt upon the completeness of Douglas’s model of spontaneous alternation.     

In the dark: Spatial choice when access to spatial cues is restricted

The cognitive mechanisms involved in spatial choice when access to visual cues is restricted were examined in three experiments using male rats. A specially constructed radial-arm maze was used, in which extramaze visual cues could not be perceived from the central arena, but could be perceived from the maze arms. Choices were very accurate when the maze was not rotated during each trial, but inaccurate when the maze was rotated. This suggests that intramaze cues were involved in the control of choices. However, the data clearly showed that choices were not simply controlled by intramaze cues. Rather, control by intramaze cues interacted in a more complex manner with representations of the spatial locations of goals. Such spatial representations were involved in the control of choice despite the absence of visual spatial cues at the time choices were made.     

Effects of varying trial distribution,intra- and extramaze cues,and amount of reward on proactive interference in the radial maze

Rats are typically less accurate in their arm selections in the radial maze over successive trials in a session (Roberts & Dale, 1981). In the present study, rats’ choice accuracy declined when such trials were separated by 2-min (massed) but not by 2-h (spaced) intertriai intervals. Changing intramaze visual/tactile arm stimuli (Experiments 1 and 3) or extramaze landmark stimuli (Experiment 4) between trials weakened the massed-trials effect, but changing the number of food pellets per arm, either alone or in conjunction with changes in intramaze cues (Experiments 2 and 3), did not. The rats also tended to avoid the spatial locations of their last four choices on a previous trial during their first four choices on a current trial, and more so with massed than with spaced trials. These findings indicate that intertriai proactive interference (PI) occurred only with massed trials and was weakened by changing intra- and extramaze cues between such trials.     

The influence of spatial irregularity upon radial-maze performance in the rat

In two experiments, we examined how the introduction of vertical or horizontal irregularities in the perfectly regular shape of a radial maze affected rats’ performances. The introduction of various tilts in each arm of an eight-arm radial maze had a slightly positive effect on accuracy. However, when intra- and extraraaze cues were dissociated by rotating the maze before maze completion, the rata relied preferentially on extramaze cues associated with the horizontal direction of the arms but not with the tilts. On the other hand, the rats showed poor performances when trained on a horizontally distorted maze (uneven angles between the arms instead of repeated 45° angles). The high number of errors was related to the neglect of particular arms, the disorganization of the patrolling sequences, and the tendency to chain the visit of five arms that formed a regular ahape. Other animals, trained in the same maze, displayed similar biases even after a pretraining phase with constrained choices. Results from the horizontally distorted maze confirm and extend data from the spontaneous alternation literature that choice behavior is influenced by rules of movement that favor large angle transitions and regular subdivisions of space. They also stress the relation between performance in the radial maze and spontaneous exploratory and foraging behaviors.     

In the dark II: spatial choice when access to extrinsic spatial cues is eliminated

Rats were tested in a specially constructed radial-arm maze that eliminated access to extramaze visual cues and allowed any effects of intramaze cues to be controlled. Despite this, choice accuracy was controlled by the spatial location of previously visited arms. Part of this control was attributed to vestibular or kinesthetic cues. This conclusion was corroborated by the finding that when explicit visual cues were moved from their standard (trained) spatial locations to novel locations, control of spatial choices was completely disrupted. The latter finding indicates that cues intrinsic to the rat (kinesthetic or vestibular information) and cues extrinsic to the rat (visual stimuli) operate in an integrated fashion.     

Attenuation by contextual cues of retroactive interference of a conditional discrimination in rats

We investigated the effect of associating unique contextual cues with an interpolated learning task on retroactive interference in long-term memory. Rats were originally trained in a two-bar operant chamber with an auditory conditional discrimination stimulus. During interpolated learning, which occurred in either the original or a new context, some rats were trained on a probability learning task that did not include the auditory stimuli present during original learning. Subsequent retraining on the original conditional discrimination task in the original context showed that (1) significant retroactive interference occurs in rats, and (2) the presence of unique contextual cues during interpolated learning significantly reduces this interference. These results extend the conditions under which the susceptibility to retroactive interference can be altered by contextual cues.     

Spatial learning by rats across visually disconnected environments

Experiments were designed in which some properties of spatial representations in rats could be examined. Adult subjects were trained to escape through a hole at a fixed position in a large circular arena (see Schenk, 1989). The experiments were conducted in the dark, with a limited number of controlled visual light cues, in order to assess the minimal cue requirement for place learning. Three light cues identical in shape, height, and distance from the table were used. Depending on the condition, they were either permanently on or alternatively on or off, contingent on the position of the rat in the field. Two questions were asked: (1) How many identical visual cues were necessary for spatial discrimination in the dark, and (2) could rats integrate the relative positions of separate cues, under conditions in which the rat was never allowed to perceive all three cues simultaneously. The results suggest that rats are able to achieve a place discrimination task even if the three cues necessary for efficient orientation can never be seen simultaneously. A dissociation between the discrimination of the spatial position of the goal and the capacity to reach it by a direct path suggests that, with a reduced number of cues, prolonged locomotion might be required for accurate orientation in the environment.     

The influences of guiding cues on motor skill autonomy in rats

How does the effectiveness of guiding cues influence the development of motor skill autonomy? We utilized two sets of guiding cues (lights vs. reversed-lights conditions) that differed in their effectiveness to control a left–right leverpress sequence in rats. We separately measured the development of stimulus control by panel lights on guiding-cues trials and the development of stimulus control by practice cues on no-cue probe trials within the same sessions. Accuracy in the presence of the guiding cues was acquired faster in the lights condition than in the reversed-lights condition, but subjects in the reversed-lights condition were more able to complete the skill autonomously than those in the lights condition. Throughout acquisition, control by guiding cues and practice cues developed at the same rate in the reversed-lights condition, but control by practice cues (autonomy) developed at a slower rate than did control by guiding cues in the lights condition. At the end of training, subjects that had been exposed to the reversed-lights condition displayed higher levels of autonomy than did those exposed to the lights condition. The less effective guiding cue (reversed-lights) produced greater levels of autonomy than did the more effective cue (lights), even though control by this guiding cue developed more slowly. Thus, guiding your child by the hand too much may reduce his or her ability to complete the task independently. We discuss the similarity to prompt dependence in children with learning disabilities and transfer of stimulus control.     

Effects of sucrose concentrations on single-alternation performance in rats

In Experiment 1, rats received single-alternation training with 32% or 4% sucrose reward (Phase 1) followed by a shift in reward from 32% to 4%, and vice versa (Phase 2). In Phase 1, high reward facilitated alternation performance over low reward. In Phase 2, performance on rewarded trials increased as reward increased but was unchanged as reward decreased. Performance on nonrewarded trials showed negligible effects of shifts in reward. In Experiment 2, rats received goalbox placements with 32% or 4% sucrose alternated with nonreward in Phase 1; and in Phase 2, they received alternation runway training with the same or the opposite reward from that of placements. Performance on rewarded trials was faster, the higher the reward in runway training; performance on nonrewarded trials was slower, the higher the reward in placements. In Experiment 3, Phase 1 provided placements with 64%, 32%, 16%, or 4% sucrose or dry mash alternated with nonreward; Phase 2 provided alternation runway training with dry mash reward. Alternation prerformance developed more rapidly, the higher the sucrose concentration in placements. Only 64% sucrose produced performance superior to that for dry-mash placements.     

The effects of facial‐head cue combinations on interpersonal evaluations

Two experiments were conducted to examine the role of visual cues in interpersonal attraction and credibility. In the first study, 128 subjects viewed eight randomly ordered videotape segments of trained actors presenting a short speech accompanied by head nods, eyebrow raises, smiles, combinations of those cues, or no such cues. Ratings of the speakers on task and social attraction revealed that, as expected, the presence of any face or head cues produced more attraction than none; however, instead of the three combined cues producing the most attraction, the smiles‐head nod condition produced the greatest social attraction and the head nod only condition produced greatest task attraction; expected sex differences were largely supported. In the second study, face and head cues were performed by confederates during a live interview situation while subjects observed the interaction from behind a two‐way mirror. Results showed that smiles produced higher attraction and credibility ratings than did no smiles and nods, thus further substantiating the reward power of facial and head cues in social interaction.     

The effects of first language orthographic features on word recognition processing in English as a second language

This study investigated the possible effects of first language (L1) orthographic characteristics on word recognition in English as a second language (ESL). Case alternation was used to examine the impact of visually distorted words of different types on fluent ESL readers' word recognition in naming. Visual distortion of word shape (i.e., cAsE aLtErNaTiOn) was utilized because, although visually distorted words have lost word-shape cues, they preserve the cue value of words (i.e., spelling patterns). It, therefore, was hypothesized that if one is sensitive to alphabetic orthography, or if one's inner mechanism of processing an alphabetic word is efficient, then the visual disruption of word-shape cues should not affect one's sensitivity to sequences of letters in words. In other words, this study focused on the magnitude of the effect of case alternation in word recognition as an index of the sensitivity to alphabetic words. Results showed that the magnitude of the case alternation effect in a naming task was significantly larger for the ESL participants whose L1 is not alphabetic (i.e., Chinese and Japanese) than the ESL participants whose L1 is alphabetic (i.e., Iranians -- Persian as L1). This result seems to indicate that the Persian speakers, due to the facilitating influence of their L1 orthography, were less influenced by case alternation than the Chinese and Japanese speakers, whose L1 orthographies are not alphabetic. This finding suggests that the first language orthographic features affect the orthographic coding mechanisms (i.e., word recognition mechanisms) in a second language.     

Short-term spatial memory in honeybees

Foraging honeybees were trained individually in two-choice spatial problems. Differentially rewarded for spatial alternation in Experiment 1 (“win-shift” training), they showed instead a clear tendency to perseverate—that is, to prefer on each trial the location of reward on the immediately preceding trial. On the basis of the results of Experiments 2 and 3, in which one location was rewarded over shorter or longer series of consecutive trials, an associative interpretation of the perseveration found in the first experiment was rejected in favor of an interpretation in terms of short-term spatial memory. Experiment 4, in which the animals were rewarded on each trial for choosing either location, also showed perseveration. Honeybees, like rats, seem to remember a rewarded location recently visited, but tend to return to it rather than, like rats, to avoid it.     

Problem solving in the rat: Piecemeal acquisition of cognitive maps

The purpose of this experiment was to compare the problem-solving performance of rats allowed to explore either one or two tables of Maier’s three-table-problem apparatus on successive days. The feeding experience and test trial were administered on the day after all tables and runways had been explored in this piecemeal fashion. No rat that explored only one table and runway per day was able to solve the problem, whereas 60% of the rats that explored two tables and their interconnecting runways did solve the problem. All rats that explored the entire apparatus on each exploratory day were able to solve the problem. These data support the notion that animals can conceptually link objects experienced successively into cognitive representations which specify the constant relationships existing between those objects. The existence of such an absolute spatial mechanism makes it unnecessary for an organism to depend upon relative spatial mechanisms such as routes or cues.     

Time-place learning in the eight-arm radial maze

Rats (n=4) searched for food on an eight-arm radial maze. Daily 56-min sessions were divided into eight 7-min time zones, during each of which a different location provided food; locations were randomized across subjects before training. The rats obtained multiple pellets within each time zone by leaving and returning to the correct location. Evidence that the rats had knowledge about the temporal and spatial features of the task includes the following. The rats anticipated locations before they became active and anticipated the end of the currently active locations. The rats discriminated currently active locations from earlier and forthcoming active locations in the absence of food transition cues. After the rats had left the previously active location, they visited the next correct location more often than would be expected by chance in the absence of food transition cues. The rats used handling or opening doors as a cue to visit the first location and timed successive 7-min intervals to get to subsequent locations.     

Memory for spatial and local cues: A comparison of a storing and a nonstoring species

Two passerine species, black-capped chickadees (Parus atricapillus, a food-storing bird) and darkeyed juncos (Junco hyemalis, a nonstoring bird) were compared in a task in which they inspected four feeders in an aviary. Different feeders and different spatial locations were used on each trial. One of the feeders was baited. The subjects returned after a 5-min retention interval to find the baited feeder. Tests with transformations of the feeder array made it possible to determine what cues controlled the food-finding behavior. Chickadees responded to spatial cues preferentially over local color and pattern cues associated with the feeder (Experiments 2–4). The same ordering of responding was found in Experiment 1, a food-storing version of the food-finding task outlined above. Experiment 5 tested juncos on the food-finding task. Juncos responded to all types of information equally. The results are discussed in relation to the notion that because of their food-storing lifestyle, chickadees may need to rely more heavily on spatial cues than do juncos.     

Cues for spontaneous alternation by gerbils

Twenty male Mongolian gerbils (Meriones unguiculatus) were tested for spontaneous alternation behavior in a T-maze under five cue conditions: (1) all cues present, (2) only S’s own odor trail, (3) only orientation cues, (4) no cues, (5) only another S’s odor trail. Significant alternation was found only in the first two conditions, indicating that odor trail is the only alternation cue for gerbils under testing conditions which also yield considerable orientation alternation in rats. There was also a tendency for gerbils to “alternate” the odor trail left by the noncagemate, but to follow that of a cagemate. A previous failure to find evidence of alternation in gerbils may have been due to a lack of opportunity for the animals to engage in trail-marking behavior.     

In a daily time–place learning task,time is only used as a discriminative stimulus if each daily session is associated with a distinct spatial location

It is difficult for rats to acquire daily time–place (TP) learning tasks. One theory suggests that rats do not use time of day as a stimulus signaling a specific response. In the present study, we tested rats’ ability to use time of day as a discriminative stimulus. A fixed-interval procedure was used in which one lever provided reinforcement on a FI-5-s schedule in morning sessions, and the same lever provided reinforcement on a FI-30-s schedule in afternoon sessions. Because only one place was used in this paradigm, the rats could only use time of day to acquire the task. Mean responses during the first 5 s of the first trial in each session indicated that the rats did not discriminate between the two sessions. In Phase II, a different lever location was used for each of the two daily sessions, which meant that both spatial and temporal information could be used to acquire the task. The rats readily acquired the task in this phase, and probe trials indicated that the rats were using a combination of spatial and temporal information to discriminate between the two different trial types. When the spatial cue was removed in Phase III, rats no longer discriminated the two sessions, suggesting that time can only be used as a discriminative stimulus when each daily session is associated with a distinct spatial location.