While navigating home, homing pigeons can extract directional, that is, compass, information from the earth's magnetic field. This navigational mechanism may begin with a peripheral transduction process based on iron-containing macrophages located in the liver. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Nonhuman animals, like humans, often prefer smaller immediate reward over larger delayed reward, suggesting "discounting" of future reward. In studies of nonhuman animals, this preference is measured by offering repeated choices between icons resulting in smaller immediate or larger delayed reward. One possible mechanism driving discounting behavior is that subjects forget during the delay to reinforcement which option they chose at the beginning of the trial. If this account is correct, preventing forgetting should decrease apparent discounting. In Experiment 1, we tested this hypothesis by having monkeys choose between immediate and delayed reward with either a blank delay to reinforcement or with the chosen icon visible during the delay such that the icon could potentially remind monkeys of their choice. When the chosen icon remained visible, apparent discounting was significantly reduced. This result suggested that reminding was effective. However, keeping the chosen icon visible during the delay also meant that the icon was visible immediately prior to reward, potentially causing the icon to accrue more associative strength with reward than would occur when there was a temporal gap between the icon and reward. Experiment 2 distinguished between reminding and associative learning by hiding the icon after selection and briefly showing it before reward delivery. Apparent discounting remained attenuated. These results indicate that the conditioning-delay gradient is a strong determinant of the choices of monkeys in delay discounting paradigms and indicate that animal models may not capture the processes proposed to explain delay discounting in humans, such as impulsivity. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
The redundant signals effect was examined in a visual search task with pigeons. In Experiment 1, pigeons searched for a fixed target among homogeneous, identical distractors that differed from the target on one of two dimensions. Target-distractor discriminability varied across trials, resulting in trial-by-trial changes in search difficulty. When set size increased at test, the relationship between response time and difficulty followed an inverted U-shaped function: Pigeons responded quickly but inaccurately on the most difficult trials, most slowly on trials of intermediate difficulty, and quickly and accurately on easy trials. With smaller set sizes, response time remained flat despite large variation in difficulty. In Experiment 2, the target differed redundantly from distractors on both dimensions, and performance was compared with that on single-cue trials. On difficult trials, redundant cues produced slower but more accurate search than single-cue trials, indicating a time-investing enhancement consistent with a speed-accuracy tradeoff. On trials of intermediate difficulty, redundant cues reduced response time while maintaining high accuracy, demonstrating the typical time-saving enhancement. However, this time-saving benefit diminished as the cues were more salient and the search difficulty on the corresponding single-cue trials decreased. Search efficiency, measured as the slope of response time as a function of set size, was determined solely by the most salient cue. These findings suggest that the two forms of redundancy enhancement arise from distinct processing loci and emerge automatically when individually learned cues are combined. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Despite the observation that temporal variables (e.g., the time between rewards) modulate the speed of associative learning, dopamine-based learning models have largely treated learning rate as a free parameter, and neither behavioral nor neural theories have quantitatively described this link. Burke et al. (2026) rigorously demonstrated that the rate of behavioral and dopaminergic cue-reward learning scales proportionally, and directly, with the interreward interval, revealing implications for how learning rate is formalized in both behavioral and dopamine-based models. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Understanding how outcome affective value influences Pavlovian learning is critical for elucidating the mechanisms underlying human emotional learning. In this study, participants completed a Pavlovian conditioning task involving outcomes varying in their level of aversiveness: a tactile (nonaversive) or painful (aversive) shock, and no-shock. Skin conductance responses (SCRs), explicit pleasantness ratings of each CS, and CS-outcome contingency ratings were recorded. Although both painful and tactile outcomes elicited unconditioned SCRs, with greater responses for the former, only the painful outcome triggered anticipatory conditioned SCRs and robust prediction error-related SCRs following its unexpected omission. Computational modeling, through a Rescorla-Wagner model, revealed that prediction errors estimated by the model significantly predicted SCRs following painful outcome omissions, confirming their role as prediction error signals. In addition, the model-derived outcome sensitivity parameter, reflecting the affective value assigned to the different outcomes by each participant, was higher for painful than tactile stimuli, effectively discriminating between them, whereas learning rates did not differ across outcomes. These findings refine our understanding of emotional learning by showing how the affective value of the outcome shapes the predictive mechanisms underlying conditioned responding, as revealed through converging autonomic, explicit, and computational modeling evidence. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Bastos and Krupenye (2026, Science, 391: 583-586) present an innovative series of studies in which they explore the capacity of a single enculturated bonobo, Kanzi, to represent pretend objects-in other words-"imagination." Their experiments involved pantomimed actions of pouring and emptying juice or placing and dumping out grapes from transparent cups or bowls and asking Kanzi to indicate where the juice or grape would remain, indicating that he was tracking an imagined object, but they failed to account for cuing or alternative explanations. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Perceptual learning can be defined as a relatively permanent change in discrimination performance as a result of experience or exposure. One key index of perceptual learning is the intermixed-blocked effect in which exposure to two ambiguous or perceptually similar stimuli (i.e., AX and BX) exposed in an intermixed fashion (AX, BX, AX, BX, AX, BX) produces enhanced discrimination performance compared with blocked exposure (AX, AX, AX, BX, BX, BX). Previous imaging data have implicated multiple brain regions in the intermixed-blocked effect. In the present study, transcranial direct current stimulation was used to explore the causal relationship of two regions, the dorsolateral prefrontal cortex (DLPFC) and the posterior parietal cortex (PPC), to performance. A mixed, double-blind, design administered two online sessions of transcranial direct current stimulation (active and sham) to 48 participants, although they viewed pairs of similar stimuli. Half of the participants received active stimulation to the DLPFC, and the other half to the PPC. Anodal stimulation in either the DLPFC or the PPC provided no modulation of discrimination performance relative to sham stimulation. These results potentially question the generality of the interpretation of other studies in which stimulation of these areas does impact on other indices of perceptual learning. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Recent evidence shows that naïve domestic chicks match sounds to shapes in ways strikingly similar to humans. Theoretical accounts linking the bouba-kiki effect to physical regularities in the environment suggest that cross-modal correspondences may reflect deep perceptual principles rather than linguistic conventions. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Rewards strengthen behaviors they follow. This principle, articulated in Thorndike's Law of Effect, is foundational to behavioral science-but it obscures two different ways behaviors may be strengthened. First, and axiomatic, is that the frequency of rewarded behaviors increases. Second, but less well established, is that the variability of rewarded behaviors decreases. Indeed, since Thorndike's pioneering research, investigations into behavioral variability have posed a challenging theoretical puzzle: Some indicate a winnowing of behavioral variants, whereas others suggest an ongoing waxing and waning of even dominant behavioral variants throughout rewarded training. We devised a new experimental task which allowed us to monitor pigeons' sequential pecking of five visually distinctive touchscreen buttons, with all sequences delivering food reward. The 120 possible five-peck sequences we monitored over 250 daily sessions produced a rich set of data to help solve this puzzle. We found that pigeons did decrease the diversity of the sequences they performed. Nevertheless, pigeons continued to perform many different sequences-with even the most dominant sequences frequently rising and falling. These findings and others in diverse realms of behavioral science, neuroscience, and computer science suggest a far-reaching solution to this puzzle: The form and frequency of consistently rewarded behavior involve a dynamic adaptive balance between stability produced by the Law of Effect and variability induced by a persistent exploratory predisposition. Called "the edge of chaos," this balance point preserves responses that reliably secure rewards and engenders behavioral flexibility in the event that the prevailing contingencies change or better options arise. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Temporal patterns of experiences dictate the depths and rates of learning, forgetting, and extinction but the biological processes involved are fundamentally unknown. Kukushkin et al. (2024) demonstrate that nonneuronal cells in culture can provide a molecular read out of temporal differences in stimulation patterns and therefore provide a tractable model system with which to rigorously investigate how cells time. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
The expression of an association between a conditioned stimulus (CS) and an aversive unconditioned stimulus (US) can be weakened by presenting the CS by itself (extinction [Ext]), pairing it with an appetitive US (counterconditioning [CC]), or pairing it with a neutral stimulus (novelty-facilitated extinction [NFE]). The present research tested whether NFE is less susceptible to ABC renewal than Ext and CC. In two experiments, participants viewed streams of rapid trials. After each stream, participants rated how likely it was that the target CS would be followed by the target US (i.e., predictive learning) as well as the valence of the target CS (i.e., evaluative conditioning). A stream was composed of two phases: Phase 1 established an association between the target CS and target US while Phase 2 aimed at disrupting the expression of this association through Ext, CC, or NFE. Phase 1 occurred in Context A while Phase 2 occurred in Context B. Prediction and valence ratings occurred in either Context A, B, or C. Neither Experiment 1 nor Experiment 2 found differences across interference conditions with predictive testing, regardless of test context. In Experiment 2, better controlled for context effect, CC and NFE altered the CS valence (CC more than NFE) when testing occurred in B, but the difference disappeared when testing occurred in either A or C. The present data do not support the hypothesis that NFE is less susceptible to ABC renewal than either Ext or CC. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Sequential information processing by animals is a fundamental component of understanding cognition in nonhuman species. Auditory processing is especially important given its implications for acoustic communication, language, and music evolution. In two experiments using an auditory go/no-go procedure, we examined how pigeons processed same/different (S/D) sound sequences. Experiment 1 tested three pigeons with blocked, recurring, or cyclic organizations of two, three, four, or six elements within sequential presentations of 12 1.5-s sounds. Experiment 2 tested four pigeons and examined how midsequence S/D transitions affected ongoing discrimination using contrasting priming strings of varying lengths. Both experiments revealed the birds' ongoing sensitivity to auditory S/D presentations, with the strongest influence exerted by more recently experienced items. The experimental data and subsequent computational modeling suggested pigeons used working memory limited to the last three to four sounds, spanning 4-6 s, to judge the S/D property. These results have important implications for different hypotheses regarding the structure and processing of cross- and multimodal S/D discriminations. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
The peak-interval procedure is one of the most widely used paradigms to assess interval timing in animal models, and disruptions in performance are commonly interpreted as disruptions in the timing mechanism. The time-sharing model (TSM) accounts for such changes by proposing that attentional resources are shared between temporal processing and the processing of novel events, producing pulse loss in the accumulator and leading to rightward shifts in peak time and decreases in response rate. According to the TSM, sustained changes in the temporal cue should induce continuous pulse loss and a marked degradation of temporal control. The present study tested these predictions by exposing pigeons to a peak-interval procedure in which the intensity of the temporal cue was parametrically varied throughout the trial. In Experiment 1, increases in signal intensity preserved response distributions centered near the trained interval, albeit with increased dispersion, whereas decreases in intensity produced irregular distributions, greater divergence from baseline performance, and longer response latencies. Experiment 2 showed that pigeons can acquire and maintain temporal control under low-intensity signals when explicitly trained, while preserving the same asymmetry between intensity increments and decrements. Together, these findings are not fully consistent with the predictions of the TSM and indicate that parametric variations in signal intensity primarily modulate the likelihood and consistency with which timing behavior is expressed. These results highlight the importance of considering nontiming behaviors, motivational factors, and variability when interpreting performance in peak-interval procedures and suggest the consideration of a dissociative modular hypothesis of performance as a complementary framework. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
In an operant feature-positive discrimination, a response during a target stimulus (A) is reinforced when presented with a feature stimulus (X), but not when presented alone (XA+/A-). When the feature and the target occur simultaneously, direct control of the response by X is typically observed, whereas serial pairings produce occasion setting. The present experiment evaluated the effects of the temporal arrangement and spatial stability of the target in a spatial task with pigeons. On separate trials, Features W and X (display color) were simultaneously presented with Landmarks A and B (visual icons) displayed at the same location (out of a row of eight locations) across trials, and pecks at the same response box were reinforced on every trial (goal; simultaneous/static). On other trials, Features Y and Z preceded the onset of Landmarks C and D, which varied in their location across trials, and the reinforced response box was positioned relative to the landmark (serial/dynamic). Transfer tests compared responding to features and landmarks with similar (i.e., W:B, X:A, Y→D, Z→C; Test 1) or different (i.e., W:D, X:C, Y→B, Z→A; Test 2) training histories. Test 1 revealed evidence more consistent with occasion setting during serial/dynamic transfer, whereas evidence more consistent with direct control was observed during simultaneous/static transfer. Test 2 revealed asymmetries in transfer when the features and the targets from different training histories were tested. The results are largely consistent with past research, but testing within a spatial task allowed for an analysis of whether and where responses occurred. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Goal-driven spatial reorientation in rectangular arenas, with or without landmarks, relies on metric attributes and environmental cues aligned with left-right orientation. Although the phenomenon has been documented in several vertebrates, its mechanisms remain little explored; in reptiles, however, neither the phenomenon nor its mechanisms have been investigated. This study tested whether spatial geometry and exploratory strategies shape reorientation in Hermann's tortoise (Testudo hermanni). Individuals were trained in a rectangular arena to locate a food reward by selecting either two geometrically symmetric corners ("No Blue Wall") or a single corner marked by a blue landmark positioned nearby ("Blue Wall Near") or at a greater distance ("Blue Wall Far"). Tortoises successfully learned to reorient using both geometric and landmark information, adopting consistent strategies to reach the goal. Qualitative observations revealed lateralized wall-following routines and a preference for perimeter exploration. Quantitatively, tortoises in the "Blue Wall Near" condition executed fewer turns, moved faster, and reached the target more quickly than those in the "Blue Wall Far" or "No Blue Wall" conditions, indicating that close proximity to a visual cue enhances spatial efficiency. In contrast, when landmarks were absent, individuals relied more heavily on geometric properties of the arena, following longer and less direct paths. Moreover, the "Blue Wall Near" condition promoted edge-following behavior, suggesting that nearby boundaries further support navigation. These findings demonstrate that reptiles can flexibly integrate geometric and landmark cues during spatial reorientation, underscoring the role of movement in shaping spatial strategies and providing novel insights into the cognitive processes underlying navigation. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Speech comprehension studies in dogs can potentially shed new light on the evolution of language and on developmental processes that make word learning possible. Interpreting the results of such experiments is complicated, however, by the wide variety of learning and generalization mechanisms that dogs may rely on during tests of their understanding. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
The partial reinforcement extinction effect (PREE) occurs when conditioned responses that were acquired with partial (inconsistent) reinforcement (PRf) extinguish more slowly than responses acquired with continuous (consistent) reinforcement. Sequential theory (Capaldi, 1966, 1994) offers the most popular account of the PREE-that, under PRf, subjects learn that they are reinforced after experiencing sequences of nonreinforcement, and this promotes continued responding during extinction. Recently, Jiao and Harris (2024) showed that rats could learn to anticipate reinforcement after a sequence of nonreinforced trials, but for these rats, being able to predict reinforcement reduced the PREE. However, it is possible that those rats learned to anticipate reinforcement based on time intervals rather than trial sequences. This issue was addressed in the present study. Four groups of rats were trained with both a continuous (consistent) reinforcement and PRf stimulus, and the timing and sequences of reinforcement were systematically manipulated between groups. The results showed that rats used temporal intervals, and not sequences, to predict reinforcement of the PRf stimulus, which calls into question previous findings for sequence learning and directly challenges the main premise of sequential theory. Moreover, during subsequent extinction, a PREE was only observed in groups that had not been able to predict reinforcement. The findings suggest that the PREE depends on uncertainty about reinforcement, and thus increased certainty about reinforcement makes the absence of reinforcement more informative, which promotes faster extinction learning. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
A recent study provided evidence for emotional contagion in bumble bees, thus raising questions about the evolutionary origins of emotions and their social components. Although evidence for affective contagion is compelling, the mechanisms and cues allowing this emotional transfer remain unclear and require further exploration. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Six experiments with human participants explored the effects of a reinforcer devaluation procedure on the microstructure of free-operant schedule performance, which is theoretically and empirically novel. The goal was to test whether different aspects of the microstructure of free-operant responding would be differentially affected by the manipulation to test the view that bout-initiation responses can be regarded as stimulus-driven habits both susceptible to devaluation, and within-bout responses as goal-directed actions that are susceptible to such effects. Humans responded to a fictitious investment game in which responses made investments in two countries with different currencies. These currencies had an exchange rate into Great British Pound (GBP), which could be manipulated to devalue the currency (reinforcer). In Experiments 1a and 2, random ratio schedules showed overall devaluation effects, which were limited to within-bout rates and more pronounced on longer ratios. In Experiments 1b and 3, random interval schedules showed limited devaluation effects, overall, except for with shorter intervals. This effect was seen on some schedules for within-bout responding. Experiments 4 and 5 manipulated the response-reinforcer feedback function (Experiment 4) and participants' ability to experience contingency variations by pretraining to be variable or static in response rates (Experiment 5). Only when there was a stronger response-reinforcer relationship (Experiment 4), which could be experienced due to variable responding (Experiment 5), did the devaluation effect occur, and these effects were limited to within-bout responses. These data suggest that an account of free-operant responding based on there being, at least, two classes of response-bout initiations that are stimulus-driven habits, and within-bout responses that are goal-directed actions-may explain many schedule effects. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Two experiments examined the hypothesis that reinstatement, the recovery of an extinguished response to a cue with the introduction of the unsignaled outcome used in conditioning, can result from context-outcome associations changing between extinction and testing resulting in a renewal of responding to the extinguished cue. The experiments manipulated whether context-outcome associations at testing were the same as those in conditioning or extinction. Using a space-shooter video game, participants learned to press a key in response to a spaceship (O1) which was signaled by a sensor cue (R) in conditioning and then received extinction where R appeared alone. In both phases, context-outcome associations were manipulated by unsignaled presentations of another spaceship (O2, associated with a different key), or its absence. In a third phase, context-outcome associations in the absence of R and O1 were manipulated to be the same as those in conditioning or extinction. When O2 was present during conditioning and immediately before test, but absent in extinction, a strong recovery of extinguished R-O1 responding was observed. When O2 was absent during conditioning and immediately before testing, but present in extinction, a smaller recovery of R-O1 was observed. When a new spaceship (O3) was introduced immediately before testing, a recovery of R-O1 was observed only if O2 had been present in conditioning, suggesting that the effects observed were not simply disinhibition of responding. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
