Pigeons see correspondence between objects and their pictures

The extent to which nonhumans recognize the correspondence between static pictures and the objects they represent remains an interesting and controversial issue. Pictures displayed on computers are used extensively for research on behavioral and neural mechanisms of cognition in birds, yet attempts to show that birds recognize the objects seen in pictures have produced mixed and inconclusive results. We trained pigeons to discriminate between two identically colored but differently shaped three-dimensional objects seen directly or as pictures, and we found clear bidirectional transfer of the learned object discrimination. Transfer from objects to pictures occurred even when pigeons were trained with 12 views and only novel views of the objects were presented in transfer. This study provides the strongest evidence yet that pigeons can recognize the correspondence between objects and pictures.     

Perception of coherent motion in random dot displays by pigeons and humans.

Pigeons and humans were required to discriminate coherent from random motion in dynamic random dot displays. Coherence and velocity thresholds were determined for both species, and both thresholds were found to be substantially higher for pigeons than for humans. The results are discussed with reference to differences in motion processing in mammals and birds. It is suggested that the inferior motion sensitivity of pigeons can be attributed to poorer spatiotemporal motion integration.     

When good news leads to bad choices

Pigeons and other animals sometimes deviate from optimal choice behavior when given informative signals for delayed outcomes. For example, when pigeons are given a choice between an alternative that always leads to food after a delay and an alternative that leads to food only half of the time after a delay, preference changes dramatically depending on whether the stimuli during the delays are correlated with (signal) the outcomes or not. With signaled outcomes, pigeons show a much greater preference for the suboptimal alternative than with unsignaled outcomes. Key variables and research findings related to this phenomenon are reviewed, including the effects of durations of the choice and delay periods, probability of reinforcement, and gaps in the signal. We interpret the available evidence as reflecting a preference induced by signals for good news in a context of uncertainty. Other explanations are briefly summarized and compared.     

Using perceptrons to explore the reorientation task

The reorientation task is a paradigm that has been used extensively to study the types of information used by humans and animals to navigate in their environment. In this task, subjects are reinforced for going to a particular location in an arena that is typically rectangular in shape. The subject then has to find that location again after being disoriented, and possibly after changes have been made to the arena. This task is used to determine the geometric and featural cues that can be used to reorient the agent in the arena. The purpose of the present paper is to present several simulation results that show that a simple neural network, a perceptron, can be used to generate many of the traditional findings that have been obtained using the reorientation task. These results suggest that reorientation task regularities can be explained without appealing to a geometric module that is a component of spatial processing.     

Odometry and backtracking: social and individual navigation in group foraging desert harvester ants (Veromessor pergandei)

Animal Cognition - Veromessor pergandei harvester ants are group foragers which use a combination of social cues (pheromone-marked columns) and individual cues (e.g., self-generated movement,...     

Distortions in location memory

Memory for the location of a briefly presented target is often distorted in systematic ways. When people remember dot locations within a circular space, they typically show memory biases that appear to reflect a categorical strategy. However, memory for a target location can also be biased toward visible markers or landmarks. In the present study, we investigated the interaction of categorical and landmark effects by providing sectioning lines in a circular space. In the absence of lines, response biases showed categorical effects, whereas in the presence of lines, response biases suggested that participants used a landmark-based scheme. Possible relations between the strategies are discussed.     

Spatial generalization and peak shift in humans

Using a computer betting game, five experiments tested university students on spatial generalization and peak shift. On each trial, one location was marked and the subject was invited to bet 0-4 points. At the winning location (S+), bets won four times the points betted. At nearby losing locations (S−s), points betted were lost. Generalization gradients were exponential in shape, supporting Shepard's (1987), law (Experiment 1). With peak shift manipulations, three kinds of peak shift or area shift were found. (1) Subjects betted more on the S+ side than on the S− side (Experiments 2-4). (2) When asked if a location was the winning location, subjects responded “yes” more often to locations on the S+ side than to locations on the S− side (Experiments 3-5). (3) When asked to point to the winning location on the screen, subjects' errors indicated peak shift (Experiment 5).     

Choice between reliable and unreliable reinforcement alternatives revisited: Preference for unreliable reinforcement

Pigeons' choices between a reliable alternative that always provided food after a delay (i.e., 100% reinforcement) and an unreliable one that provided food or blackout equally often after a delay (i.e., 50% reinforcement) was studied using a discrete-trials concurrent-chains procedure modified to prevent choice between alternatives following a blackout outcome. Initial links were fixed-ratio 1 schedules, and terminal links were fixed-time schedules. Stimuli presented during the terminal-link delays were correlated with the food and blackout outcomes. In Experiment 1, terminal-link durations were varied. With short terminal links (i.e., 10 s), 6 of 8 subjects showed strong preference for the 50% side. As terminal-link duration increased to 30 s, preference, regardless of direction, became less extreme. In Experiment 2, the side-key location of the 50% and 100% alternatives was reversed for 3 subjects. Preference for the 50% alternative reoccurred following the key reversal. When a 5-s separation was subsequently interposed between the initial and terminal links for both alternatives, all birds reversed to a preference for the 100% side. In general, the strong preference for the 50% side was qualitatively consistent with the expectation that the procedure enhanced the conditioned-reinforcement effectiveness of the food-associated terminal-link stimulus on the 50% side. Implications of the results for various accounts of choice of the 50% alternative are discussed.