Kenneth J. Leising

Causal Reasoning in Rats

Empirical research with nonhuman primates appears to support the view that causal reasoning is a key cognitive faculty that divides humans from animals. The claim is that animals approximate causal learning using associative processes. The present results cast doubt on that conclusion. Rats made causal inferences in a basic task that taps into core features of causal reasoning without requiring complex physical knowledge. They derived predictions of the outcomes of interventions after passive observational learning of different kinds of causal models. These competencies cannot be explained by current associative theories but are consistent with causal Bayes net theories.

Sensory preconditioning in spatial learning using a touch screen task in pigeons.

The authors used a touch screen-based visual-search task to investigate spatial integration in pigeons. First, pigeons were presented with a consistent spatial relationship between compound visual landmarks (LMs) A-X and B-Y, separately. Next, pigeons learned to find a hidden goal on the monitor in the presence of LMs A and B. The goal bore a consistent spatial relationship to LM A, but not to LM B. On nonreinforced probe tests, the peak and distribution of responses to LM X suggest that pigeons computed a novel X-goal spatial relationship on the basis of X-A and A-goal spatial vectors. Responses to LM Y, however, revealed no evidence of spatial integration. These results replicate and extend those of A. P. Blaisdell and R. G. Cook (2005) using an open-field task.

The Special Status of Actions in Causal Reasoning in Rats

A. P. Blaisdell, K. Sawa, K. J. Leising, and M. R. Waldmann (2006) reported evidence for causal reasoning in rats. After learning through Pavlovian observation that Event A (a light) was a common cause of Events X (an auditory stimulus) and F (food), rats predicted F in the test phase when they observed Event X as a cue but not when they generated X by a lever press. Whereas associative accounts predict associations between X and F regardless of whether X is observed or generated by an action, causal-model theory predicts that the intervention at test should lead to discounting of A, the regular cause of X. The authors report further tests of causal-model theory. One key prediction is that full discounting should be observed only when the alternative cause is viewed as deterministic and independent of other events, 2 hallmark features of actions but not necessarily of arbitrary events. Consequently, the authors observed discounting with only interventions but not other observable events (Experiments 1 and 2). Moreover, rats were capable of flexibly switching between observational and interventional predictions (Experiment 3). Finally, discounting occurred on the very first test trial (Meta-Analysis). These results confirm causal-model theory but refute associative accounts.

Temporal integration in Pavlovian appetitive conditioning in rats

We used an appetitive sensory preconditioning procedure to investigate temporal integration in rats in two experiments. In Phase 1, rats were presented with simultaneous compound trials on which a 10-sec conditioned stimulus (CS) X was embedded within a 60-sec CS A. In Group Early, CS X occurred during the early portion of CS A, whereas in Group Late, CS X occurred during the latter portion of CS A. In Phase 2, CS X was paired simultaneously with sucrose. On a subsequent test with CS A, the rate of magazine entries peaked during the early portions of the stimulus in Group Early and during the latter portions of the stimulus in Group Late (Experiments 1 and 2). Similar response peaks were not observed on tests with a control stimulus that had been presented in compound with a stimulus that did not signal reward (Experiment 2).

Overshadowing between landmarks on the touchscreen and in arena with pigeons.

The role of generalization decrement in spatial overshadowing was evaluated using a landmark-based spatial search task in both a touchscreen preparation (Experiment 1a) and in an Automated Remote Environmental Navigation Apparatus (ARENA, Experiment 1b). A landmark appeared as a colored circle among a row of eight (touchscreen) or six (ARENA) potential locations. On overshadowing trials, Landmark X was located two positions away from a hidden goal, while another landmark, A, was in the position between X and the goal. On control trials, Landmark Y was positioned two locations away from the goal but without a closer landmark. All subjects were then tested with separate trials of A, X, Y, and BY. Testing revealed poor spatial control by X relative to A and Y, thereby replicating the spatial overshadowing effect. Spatial control by Y was similar when tested in compound with novel landmark (BY) and on trials of Y alone. Thus, overshadowing in a small-scale environment does not appear to be due to a process of generalization decrement between training and testing.

Explorations of object and location memory using fMRI

Content-specific sub-systems of visual working memory (VWM) have been explored in many neuroimaging studies with inconsistent findings and procedures across experiments. The present study employed functional magnetic resonance imaging (fMRI) and a change detection task using a high number of trials and matched stimulus displays across object and location change (what vs. where) conditions. Furthermore, individual task periods were studied independently across conditions to identify differences corresponding to each task period. Importantly, this combination of task controls has not previously been described in the fMRI literature. Composite results revealed differential frontoparietal activation during each task period. A separation of object and location conditions yielded a distributed system of dorsal and ventral streams during the encoding of information corresponding to bilateral inferior parietal lobule (IPL) and lingual gyrus activation, respectively. Differential activity was also shown during the maintenance of information in middle frontal structures bilaterally for objects and the right IPL and left insula for locations. Together, these results reflect a domain-specific dissociation spanning several cortices and task periods. Furthermore, differential activations suggest a general caudal-rostral separation corresponding to object and location memory, respectively.

Visual discrimination learning with an iPad-equipped apparatus.

Visual discrimination tasks are commonly used to assess visual learning and memory in non-human animals. The current experiments explored the suitability of an iPad (Apple, Cupertino, California), as a low-cost alternative touchscreen for visual discrimination tasks. In Experiment 1, rats were trained with patterned black-and-white stimuli in a successive non-match to sample procedure. Rats successfully interacted with the iPad but failed to learn to withhold responding on trials in which the sample matched the comparison. Experiment 2 used the same patterned stimuli, but the procedure was simplified to a successive discrimination procedure and we explored the use of procedures known to facilitate discrimination learning. Rats that received training with differential outcomes and a differential reinforcement of other behavior schedule successfully acquired the task. In Experiment 3, the same rats were tested in a simultaneous discrimination task and we explored the use of a correction and non-correction method during acquisition. Rats that failed to learn the discrimination in the previous experiment, improved while trained with the correction method. These experiments support the use of the iPad in visual discrimination tasks and inform future studies investigating learning and memory within a touchscreen-equipped (iPad or other) apparatus.

Factors that influence negative summation in a spatial-search task with pigeons

A variant of the standard conditioned inhibition procedure was used to evaluate landmark-based spatial search in a touchscreen preparation. Pigeons were given compound trials with one landmark (A) positioned in a consistent spatial relationship to a hidden goal and another landmark (B) positioned randomly with respect to A and the hidden goal (AB+). On half of the non-reinforced inhibitory trials, A was paired with landmark X (AX-) and on the remaining trials B was paired with Y (BY-). All subjects were also given reinforced trials with a transfer excitor (T+). During conditioned inhibition training, subjects showed no change in overall responding during AX- trials but did show a decrease in the number of pecks to the goal location signaled by A. During non-reinforced summation tests with landmark T, X had a greater suppressive effect than did Y on overall responding but the percentage of pecks at the goal did not differ unless X was positioned near the expected goal signaled by T. These data demonstrate that the effectiveness of a stimulus trained as an inhibitor is dependent on the strength of the association between its training excitor (A) and the US, as well as, the spatial arrangement of stimuli during testing.

Behavioral research in pigeons with ARENA: An Automated Remote Environmental Navigation Apparatus

Three experiments established the effectiveness of an Automated Remote Environmental Navigation Apparatus (ARENA) developed in our lab to study behavioral processes in pigeons. The technology utilizes one or more wireless modules, each capable of presenting colored lights as visual stimuli to signal reward and of detecting subject peck responses. In Experiment 1, subjects were instrumentally shaped to peck at a single ARENA module following an unsuccessful autoshaping procedure. In Experiment 2, pigeons were trained with a simultaneous discrimination procedure during which two modules were illuminated different colors; pecks to one color (S+) were reinforced while pecks to the other color (S-) were not. Pigeons learned to preferentially peck the module displaying the S+. In Experiment 3, two modules were lit the same color concurrently from a set of six colors in a conditional discrimination task. For three of the colors pecks to the module in one location (e.g., upper quadrant) were reinforced while for the remaining colors pecks at the other module (e.g., lower quadrant) were reinforced. After learning this discrimination, the color-reinforced location assignments were reversed. Pigeons successfully acquired the reversal. ARENA is an automated system for open-field studies and a more ecologically valid alternative to the touchscreen.

Extinction and Spontaneous Recovery of Spatial Behavior in Pigeons

We investigated extinction and spontaneous recovery of spatial associations using a landmark-based appetitive search task in a touchscreen preparation with pigeons. Four visual landmarks (A, B, C, and D) were separately established as signals of a hidden reinforced target among an 8 × 7 array of potential target locations. The target was located above landmarks (LM) A and C and below B and D. After conditioning, A and B were extinguished. Responding to A and C was assessed on probe tests 2 days following extinction, whereas, B and D were tested 14 days after extinction. We observed spontaneous recovery from spatial extinction following a 14-day, but not a 2-day, postextinction retention interval. Furthermore, by plotting the spatial distribution of responding across the X and Y axes during testing, we found that spontaneous recovery of responding to the target in our task was due to enhanced spatial control (i.e., a change in the overall distribution of responses) following the long delay to testing. These results add spatial extinction and spontaneous recovery to the list of findings supporting the assertion that extinction involves new learning that attenuates the originally acquired response, and that original learning of the spatial relationship between paired events survives extinction. (PsycINFO Database Record