Impact of equivalence class training on same/different learning by pigeons.

Separating and isolating the contributions of perception to concept formation in animals has been a long-standing and persistent challenge. Here we describe a novel approach to assessing this question by using equivalence training consisting of unrelated images as the basis for subsequent same/different (S/D) learning. Following equivalence class training, two groups of pigeons attempted to learn a go/no-go discrimination task constructed from these classes. In the go/no-go task, a consistent group was given an S/D assignment that aligned with this prior training (same vs. different classes). An inconsistent group was given go/no-go assignments that were misaligned with their established classes. The consistent group exhibited better learning and stimulus control in their S/D task than did the inconsistent group. These results suggest that pigeons can use trained properties derived from class-based information to learn an S/D task without the aid of perceptual similarity. This novel approach holds promise for helping to evaluate the contribution of perceptual similarity to different types of concept learning. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Modeling within-session dynamics of categorical and item-memory mechanisms in pigeons.

Past studies have shown that pigeons can learn complex categories and can also remember large numbers of individual objects. In recent work, Cook et al. Psychonomic Bulletin & Review, 28, 548-555, (2021) provided evidence that pigeons may use a dynamic combination of both category-based information and item-specific memorization to solve a categorical variation of the mid-session reversal (MSR) task, which is an influential task for exploring the nature of temporally organized behaviors in animals. To provide greater insight into these pigeons' behaviors, in this article we developed and investigated different computational models and their variations to account for these data. Of these, two models emerged as good candidates. One was a multinomial-processing-tree categorization/memory model, formalizing the two-process mechanism initially proposed by Cook et al. Psychonomic Bulletin & Review, 28, 548-555, (2021). The second was a new object/time-coding model, which posits the storage of object-specific memories with an additional within-session time code and assumes that a basic stimulus generalization process underlies the pigeons' choice behavior. Both provided high-quality fits to the published sets of training and transfer data collected in the categorical MSR task. These computational efforts give deeper insights into the theoretical mechanisms underlying the temporal and sequential structure of behavior in animals and stimulate future empirical research further revealing the organization of the pigeons' cognitive processes.

Same/different discrimination of motion by pigeons.

Telling that one object or moment is different from another one is fundamental to cognition and intelligent behavior. Most investigations examining same/different (S/D) concepts in animals have relied on testing static visual stimuli. To move beyond this limitation, we investigated how five pigeons learned and performed a motion S/D discrimination. Using a go/no-go task, dynamic motion fields built from dot elements were presented in sequence to display repeating (same) or changing (different) motions. Each trial consisted of 10 motion segments presented in succession using the direction and rate of dot movement in the motion field to exemplify the S/D relations. The pigeons learned this motion S/D discrimination. We further tested their performance by varying the number and persistence of the dots in the motion fields. The results indicated the pigeons likely extracted globally integrated perceptual summaries of the motions for comparison across the segments. Testing differing organizations of the S/D relations across segments indicated that this discrimination could be determined from as few as two segments and involved an updating comparison of at least four or more segments of the sequence during their presentation. Collectively, the experiments establish for the first time that pigeons can use motion features to classify sequential same and different experiences. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Learning and organization of within-session sequences by pigeons (Columba livia).

Most animals engage in complex activities that are the combination of simpler actions expressed over a period of time. The mechanisms organizing such sequential behavior have been of long-standing biological and psychological interest. Previously, we observed pigeons' anticipatory behavior with a within-session sequence involving four choice alternatives suggestive of a potential understanding of the overall order and sequence of the items within a session. In that task, each colored alternative was correct for 24 consecutive trials as presented in a predictable sequence (i.e., A first, then B, then C, then D). To test whether these four already-trained pigeons possessed a sequential and linked representation of the ABCD items, we added a second four-item sequence involving new and distinct colored choice alternatives (i.e., E first for 24 trials, then F, then G, then H) and then alternated these ABCD and EFGH sequences over successive sessions. Over three manipulations, we tested and trained trials composed of combinations of elements from both sequences. We determined that pigeons did not learn any within-sequence associations among the elements. Despite the availability and explicit utility of such sequence cues, the data suggest instead that pigeons learned the discrimination tasks as a series of temporal associations among independent elements. This absence of any sequential linkage is consistent with the hypothesis that such representations are difficult to form in pigeons. This pattern of data suggests that for repeated sequential activities in birds, and potentially other animals including humans, there are highly effective, but underappreciated, clock-like mechanisms that control the ordering of behaviors.

Dynamically occluded action recognition by pigeons.

Identifying the behaviors of organisms is essential for an animal's survival. This ability is particularly challenged when the "actors" are dynamically occluded by other objects and become fragmented as they move through an environment. Even when fragmented in time and across space, humans readily recognize the behavior of these dynamically occluded objects and actors. How animals process such fragmented information, especially when involving motion, remains uncertain. In three experiments, we investigated the ability of six pigeons to discriminate between the running and walking actions of digital animal models when dynamically occluded. The pigeons were tested in a go/no-go procedure using three models that transited behind multiple occluders in a semirealistic scene. Without ever seeing the entirety of the animal model at one time, all the pigeons learned to discriminate among these two behaviors. This discrimination transferred to an unfamiliar model, transit direction, transiting rates, camera perspectives, and occluders. Tests with different static and dynamic features indicated that the pigeons relied on motion features for the discrimination, especially articulated motion. These experiments demonstrate that pigeons, like humans, can discriminate actions even when their view of the actor is fragmented in time and space.

Mechanisms of within-session sequential behavior in pigeons.

Correctly and efficiently selecting among options is critical to the organization of behavior across different time scales (minutes, days, seasons). As a result, understanding the mechanisms underlying the sequential behavior of animals has been a long-standing aim. In three experiments, four pigeons were tested in a four-choice simultaneous color discrimination. Across a session, they had to sequentially select a colored stimulus, and the correct color changed over four 24-trial phases (A→B→C→D). After learning this ABCD within-session sequence, tests identified that both timing and outcome feedback mechanisms contributed to the organization of pigeons' behavior. Different representational mechanisms are considered as accounts for the pigeons' observed sequential behavior.

Pigeons discount continuously changing perspective during action recognition.

An important challenge for animal and artificial visual systems is separating the system's own motions from the movements of other animals or events. To examine this issue in birds, we conducted three experiments testing four pigeons in a go/no-go action discrimination. The pigeons discriminated whether a digital human model was exhibiting an extended series of articulated motions or one of a set of static poses from the same video. They were required to do so while the rendering camera's perspective changed continually during each trial's 20-s video presentation. Experiment 1 found that pigeons easily discount the camera's continuous motion. Experiments 2 and 3, by testing novel sequences of the behavior, novel behaviors, silhouettes, and a form of conditional discrimination, revealed this to be a general capacity. Overall, the discrimination was predominantly mediated by global action cues, although a small contribution of image-based statistical features was detected. Collectively, the experiments reveal pigeons can readily separate and discount constantly changing perspectives while processing others' actions. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Perceptual grouping and detection of trial-unique emergent structures by pigeons.

Detecting global patterns in the environment is essential to object perception and recognition. Consistent with this, pigeons have been shown to readily detect and locate geometrically arranged, structured targets embedded in randomized backgrounds. Here we show for the first time that pigeons can detect and localize trial-unique targets derived solely from global patterns resulting from periodicity, symmetry and their combination using randomly generated segments of black and white local elements. The results indicate pigeons can perceptually segment and detect a wide variety of emergent global structures and do so even when they are unique to each trial. The perceptual and cognitive mechanisms underlying this discrimination likely play important roles in the abilities of how pigeons, and likely other birds, detect and categorize the properties of natural objects at different spatial scales.

Use of different attentional strategies by pigeons and humans in multidimensional visual search.

To study comparative attentional allocation strategies, pigeons and humans were tested using simultaneously available discrimination tasks. Given visual search displays containing 32 items from two orthogonal dimensions, participants were reinforced for selecting the eight brightest (or darkest) of 16 brightness items and the eight most vertical (or horizontal) of 16 orientation items. Consistent with a sequential dimensional strategy, humans preferentially chose items from one dimension before switching to the other to complete the search. In contrast, the pigeons did not preferentially stay within one dimension over consecutive choices. Instead, they chose the items most likely to yield reward based on item discriminability. Computational models that incorporated a "dimensional staying" factor accounted best for the human data, while simulations using only discriminability reproduced the pigeons' data. These results suggest that humans are sensitive to the benefits of attentional staying and the costs of switching between dimensional tasks, while there was no evidence that these factors influenced the pigeons' choice behavior. These findings suggest fundamental differences in how pigeons and humans allocate attention in complex choice situations. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Adaptive testing of the critical features in 2D-shape discrimination by pigeons and starlings.

An innovative adaptive discrimination procedure examined how two bird species, pigeons and starlings, recognize and discriminate two-dimensional (2D) visual shapes. Prior results suggest a comparative divergence between mammals and birds in their relative reliance on vertices versus line segments to mediate discrimination. To address this potentially important difference, four pigeons and five starlings were tested with a square versus triangle discrimination in two experiments. An adaptive genetic algorithm guided the selection and organization of the training and test stimuli. Both species showed considerable flexibility in accurately selecting triangles despite wide variation in stimulus appearance and location. Most critically, Experiment 2 revealed that both bird species relied more on the figures' vertices during successful discrimination than their connecting line segments. This reliance was revealed by both traditional accuracy differences using contour-deleted displays and genetic algorithm-based shifts in "gene values" caused by the birds' selection. These results, in contrast to previous findings, indicate that mammals and birds likely converge in their reliance on vertices as a highly critical feature in visual shape discrimination. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Within-session dynamics of categorical and memory mechanisms in pigeons.

The current experiments used categorical mid-session reversal (MSR) to examine how eight pigeons utilized categorical and item-specific mechanisms to learn and solve a novel variation of this task. Employing a fixed order of trial-unique pictorial items from two categories (flowers and cars) on each simultaneous discrimination trial, categorical and item-specific information was available during each session's 80 trials. Choices to one category were rewarded for the first 40 trials, after which the correct category was reversed (e.g., car correct early → flower correct late). This procedure selectively impacts the time-modulated utility of categorical identification, but leaves exclusively item-specific information intact. Results revealed that categorical control emerged rapidly and before item-specific memorization, which came after extended experience. Both types of control occurred within a session, with control modulated by their time-based relative utility. The implications for the timing, ordering, and attention by animals to categorical and item-specific information is considered.

Towards describing scenes by animals: Pigeons' ordinal discrimination of objects varying in depth.

The perception of a complex scene requires visual mechanisms that include identifying objects and their relative placement in depth. To examine apparent depth perception in birds, we tested four pigeons with a novel multiple-sequential-choice procedure. We created 3D-rendered scene stimuli containing three objects located at different apparent depths based on a variety of pictorial cues and placed small circular target response areas on them. The pigeons were trained to sequentially choose among the multiple response areas to report the object closest in apparent depth (ordinal position; front then middle object). After the pigeons learned this sequential depth discrimination, their use of three different monocular depth cues (occlusion, relative size, height in field) was tested, and their flexibility evaluated using three novel objects. In addition to the contribution to understanding apparent depth perception in birds, the use of more flexible open-ended choice discriminations, as employed here, has considerable promise for creating informative production-like tasks in nonverbal animals.

Pigeons process actor-action configurations more readily than bystander-action configurations.

Behavior requires an actor. Two experiments using complex conditional action discriminations examined whether pigeons privilege information related to the digital actor who is engaged in behavior. In Experiment 1, each of two video displays contained a digital model, one an actor engaged in one of two behaviors (Indian dance or martial arts) and one a neutrally posed bystander. To correctly classify the display, the pigeons needed to conditionally process the action in conjunction with distinctive physical features of the actor or the bystander. Four actor-conditional pigeons learned to correctly discriminate the actions based on the identity of the actors, whereas four bystander-conditional birds failed to learn. Experiment 2 established that this failure was not due to the latter group's inability to spatially integrate information across the distance between the two models. Potentially, the colocalization of the relevant model identity and the action was critical due to a fundamental configural or integral representation of these properties. These findings contribute to our understanding of the evolution of action recognition, the recognition of social behavior, and forms of observational learning by animals.

Natural disasters and infectious disease in Europe: a literature review to identify cascading risk pathways.

BACKGROUND: Natural disasters are increasing in their frequency and complexity. Understanding how their cascading effects can lead to infectious disease outbreaks is important for developing cross-sectoral preparedness strategies. The review focussed on earthquakes and floods because of their importance in Europe and their potential to elucidate the pathways through which natural disasters can lead to infectious disease outbreaks. METHODS: A systematic literature review complemented by a call for evidence was conducted to identify earthquake or flooding events in Europe associated with potential infectious disease events. RESULTS: This review included 17 peer-reviewed papers that reported on suspected and confirmed infectious disease outbreaks following earthquakes (4 reports) or flooding (13 reports) in Europe. The majority of reports related to food- and water-borne disease. Eleven studies described the cascading effect of post-disaster outbreaks. The most reported driver of disease outbreaks was heavy rainfall, which led to cross-connections between water and other environmental systems, leading to the contamination of rivers, lakes, springs and water supplies. Exposure to contaminated surface water or floodwater following flooding, exposure to animal excreta and post-disaster living conditions were among other reported drivers of outbreaks. CONCLUSIONS: The cascade effects of natural disasters, such as earthquakes and floods, include outbreaks of infectious disease. The projection that climate change-related extreme weather events will increase in Europe in the coming century highlights the importance of strengthening preparedness planning and measures to mitigate and control outbreaks in post-disaster settings.

The effect of learning on heart rate and behavior of European starlings (Sturnus vulgaris).

Wild-caught European starlings (Sturnus vulgaris) were exposed to a learning task to determine whether heart rate (HR) and behavior responses to the learning activated the sympathetic nervous system. Birds learned to discriminate between images of opposite convexity (concave and convex) based on shading cues in a closed economy (food only available through task completion). Once learned, the task was changed in three ways: (a) manipulating the angle and shape of the image; (b) altering the availability of the task; and (c) reversing the positive stimulus. HR, used as an index of catecholamine release, was measured during each change to determine whether having to alter previously established behaviors to learn new behaviors elicited a sympathetic response. Starlings decreased their HR during the initial discrimination training and did not alter their HR when presented with modified images or when the positive stimulus was reversed. However, HR increased when the task became unavailable and decreased upon its return, suggesting that preventing task performance was perceived as stressful. Birds also modified their behavior when tasks were changed. The number of trials per minute decreased during the reversal treatment, as did the success rate, suggesting that starlings may try to conserve energy when access to food diminishes. This is also supported by the decrease in perch hops per minute when the task was unavailable and the subsequent increase upon its return. Overall, these results suggest that learning per se does not activate the sympathetic nervous system and, therefore, is not a stressor for wild birds.

Perception of Ebbinghaus-Titchener stimuli in starlings (Sturnus vulgaris).

Whether animals experience visual illusions is a fertile area of study for examining the evolution and operation of visual cognition across different species. Here, five starlings were tested to examine whether they experienced the Ebbinghaus-Titchener illusion. Across two experiments using an absolute target circle size discrimination, the size, similarity, distance, and number of the surrounding flankers were manipulated. The results suggest that this passerine species exhibits behavior inconsistent with the perception of the illusion, neither in a human-like fashion nor, as suggested by the first experiment, a reversed illusion. Instead, the typical training used to investigate this illusion caused the starlings to learn to integrate the irrelevant flankers into their decision process in a manner that precludes the study of illusory perception. The resulting discriminative behavior might best be described using a template-matching account. While illusion perception by animals remains an important comparative question, it requires additional validation to confirm the exact mechanisms of any illusory reports.

An identified ensemble within a neocortical circuit encodes essential information for genetically-enhanced visual shape learning.

Advanced cognitive tasks are encoded in distributed neocortical circuits that span multiple forebrain areas. Nonetheless, synaptic plasticity and neural network theories hypothesize that essential information for performing these tasks is encoded in specific ensembles within these circuits. Relatively simpler subcortical areas contain specific ensembles that encode learning, suggesting that neocortical circuits contain such ensembles. Previously, using localized gene transfer of a constitutively active protein kinase C (PKC), we established that a genetically-modified circuit in rat postrhinal cortex, part of the hippocampal formation, can encode some essential information for performing specific visual shape discriminations. However, these studies did not identify any specific neurons that encode learning; the entire circuit might be required. Here, we show that both learning and recall require fast neurotransmitter release from an identified ensemble within this circuit, the transduced neurons; we blocked fast release from these neurons by coexpressing a Synaptotagmin I siRNA with the constitutively active PKC. During learning or recall, specific signaling pathways required for learning are activated in this ensemble; during learning, calcium/calmodulin-dependent protein kinase II, MAP kinase, and CREB are activated; and, during recall, dendritic protein synthesis and CREB are activated. Using activity-dependent gene imaging, we showed that during learning, activity in this ensemble is required to recruit and activate the circuit. Further, after learning, during image presentation, blocking activity in this ensemble reduces accuracy, even though most of the rest of the circuit is activated. Thus, an identified ensemble within a neocortical circuit encodes essential information for performing an advanced cognitive task.

Pigeons simultaneously attend to static and dynamic features of complex displays.

The simultaneous processing and attention to temporally dynamic and static features remains an open and important question in theories of avian visual cognition. Here, four pigeons (Columba livia) learned to discriminate complex displays involving concurrently available static and dynamic features. These displays consisted of 20 elements built from combinations of two, binary-valued, static visual dimensions: red vs. green element color, large vs. small element size; and two binary-valued dynamic dimensions; fast vs slow element motion, right vs up motion direction. One combination of these four features was reinforced on a VI schedule. The remaining 15 combinations of element color, size, speed and direction were never reinforced. During acquisition, all four dimensions were simultaneously discriminated. Varying the number of elements revealed that a single element was sufficient to support discrimination of all four dimensions. The pigeons agreed on the relative discriminability of stimuli within and across the different dimensions, with the difference in motion direction being the hardest for all birds. Redundant facilitation suggested rapid, perhaps parallel, processing of both dynamic and static features. No attentional trade-offs between dynamic or static dimensions were observed. These results agree with theories of avian vision employing the notion of multiple independent channels for different types of information.

Testing analogical rule transfer in pigeons (Columba livia).

Categorization is an essential cognitive process useful for transferring knowledge from previous experience to novel situations. The mechanisms by which trained categorization behavior extends to novel stimuli, especially in animals, are insufficiently understood. To understand how pigeons learn and transfer category membership, seven pigeons were trained to classify controlled, bi-dimensional stimuli in a two-alternative forced-choice task. Following either dimensional, rule-based (RB) or information integration (II) training, tests were conducted focusing on the "analogical" extension of the learned discrimination to novel regions of the stimulus space (Casale, Roeder, & Ashby, 2012). The pigeons' results mirrored those from human and non-human primates evaluated using the same analogical task structure, training and testing: the pigeons transferred their discriminative behavior to the new extended values following RB training, but not after II training. Further experiments evaluating rule-based models and association-based models suggested the pigeons use dimensions and associations to learn the task and mediate transfer to stimuli within the novel region of the parametric stimulus space.

Stroke prevention in Europe: how are 11 European countries progressing toward the European Society of Cardiology (ESC) recommendations?

PURPOSE: Stroke is a leading cause of death and disability, although studies show that 90% of strokes can be prevented. The evidence base for stroke prevention is well established, and this study aimed to investigate how well European countries are adopting the European Society of Cardiology (ESC) guidelines, particularly toward implementation of the recommended best practice in stroke prevention. MATERIALS AND METHODS: We developed a stroke prevention scorecard - populated with World Health Organization (WHO) data, secondary research, time-series data, and a survey of 550 physicians - to benchmark 11 European countries in the context of the ESC guidelines. RESULTS: All countries were found to have policies in place to manage general behavioral risk factors of noncommunicable disease (NCD), but we found that more needs to be done to address cardiovascular disease - specifically, stroke risk factors. Although ten of the countries in this study endorse the ESC cardiovascular clinical guidelines, implementation is lacking. Eight out of the 11 countries received the lowest score in regard to raising awareness around stroke, and 7 countries were found not to have a stroke registry. Among physicians surveyed in primary care it was reported that less than 30% of patients over 40 years old were screened for blood pressure, whereas even fewer were screened for atrial fibrillation; in 10 out of the 11 countries, less than 20% of patients over 65 years old were screened for atrial fibrillation. CONCLUSION: Although progress is being made in managing the burden of NCDs, our findings reveal opportunities for improvement in the primary prevention of stroke. Further developments in strategic planning, raising awareness, and monitoring disease are required, as is research on barriers to the implementation of best practice screening of blood pressure and atrial fibrillation in primary care.