Comparative Cognition Research Demonstrates the Similarity between Humans and Other Animals

Abstract

The field of comparative cognition represents the interface between the cognitive behavior of humans and other animals. In some cases, research demonstrates that other animals are capable of showing similar cognitive processes. In other cases, when animals show behavior thought to be culturally determined in humans, it suggests that simpler processes may be involved. This review examines research primarily with pigeons (out of convenience because of their visual ability). I start with the concept of sameness and follow with the concept of stimulus equivalence, the building blocks of human language. This is followed by research on directed forgetting, the cognitive ability to maintain or forget information. A hallmark of cognition is transitive inference performance (if A < B, and B < C, the understanding that A < C), but the variety of species that show this ability suggests that there may be simpler accounts of this behavior. Similarly, experiments that demonstrate a form of cognitive dissonance in animals suggest that dissonance may not be necessary to explain this biased behavior. Furthermore, examples of sunk cost in pigeons suggests that the human need to continue working on a failing project may also have a biological basis. Finally, pigeons show a preference for a suboptimal choice that is similar to unskilled human gambling, a finding that may clarify why humans are so prone to engage in this typically losing activity.

Keywords: comparative cognition; equivalence; gambling; justification of effort; sameness; transitive inference.

Figure 1

Design of same/different transfer experiment. Pigeons were trained on circle-plus matching or mismatching. They were all transferred to red and green stimuli, half to the same concept they were trained on (matching to matching or mismatching to mismatching), half to the other concept (matching to mismatching or mismatching to matching). After Zentall and Hogan (1976) [12].

Figure 2

Results of same/different transfer experiment. Pigeons were trained on circle-plus matching or mismatching. They were all transferred to red and green stimuli, half to the same concept they were trained on (consistent), half to the other concept (inconsistent). After Zentall and Hogan (1976) [12].

Figure 3

Pigeons were trained on four-color matching (top) or mismatching (bottom), as shown. Then, either the incorrect stimulus was replaced with a stimulus not seen with that sample during training or the correct stimulus was replaced with a stimulus not seen with the sample during training. Test trials for the yellow, green, and blue samples not shown. After Zentall et al. (2018) [13].

Figure 4

Results of Zentall et al. (2018) [13]. Base = baseline accuracy on matching or mismatching trials. N Cor = accuracy when the correct stimulus was replaced with a new stimulus. N Inc = accuracy when the correct stimulus was replaced with a new stimulus. Error bars = ± 1 standard error of the mean.

Figure 5

Design of the stimulus equivalence experiment (Urcuioli et al., 1989 [14]). In original training, pigeons were trained to select the large circle when the sample was red or a vertical line and to select the small circle when the sample was green or a horizontal line. During interim training, they were trained to select blue when the sample was red and white when the sample was green. On test trials, they were shown vertical and horizontal lines and they selected between blue and white.

Figure 6

Directed forgetting: omission procedure. Pigeons were trained on a red/green delayed matching task. + = reinforcement. During the delay, insertion of a remember cue (r-cue) indicated that they would be tested for their memory for the sample. Insertion of a forget cue (f-cue) indicated that they would not be tested for their memory for the sample. On probe trials, they were presented with an f-cue, but were tested for their memory for the sample (after Maki and Hegvik, 1980 [23], omission group).

Figure 7

Directed forgetting: substitution procedure. Pigeons were trained on a red/green delayed matching task. + = reinforcement. During the delay, insertion of an r-cue (remember cue) indicated that they would be tested for their memory for the sample. Insertion of an f-cue (forget cue) indicated that they would not be tested for their memory for the sample, but they would have a simultaneous discrimination with reinforcement for selection of the vertical line. On probe trials, they were presented with an f-cue, but were tested for their memory for the sample (after Maki and Hegvik, [23] substitution group).

Figure 8

Directed forgetting: reallocation procedure. Pigeons were trained on a red/green delayed matching task. + = reinforcement. During the delay, insertion of an r-cue (remember cue) indicated that they would be tested for their memory for the sample. Insertion of one of two f-cues (forget cues) indicated that they would not be tested for their memory for the sample, but they would have to remember the forget cue (after Roper, Kaiser, and Zentall, 1995) [29].

Figure 9

Design of the justification-of-effort experiment with pigeons: On some trials, a single peck was required to present a simple simultaneous (red/yellow) discrimination. On other trials, 20 pecks were required to present a simple simultaneous (green/blue) discrimination. On probe trials, pigeons were given a choice between the two former positive stimuli (after [53]).

Figure 10

Design of the suboptimal choice experiment with pigeons using differential magnitude of reinforcement. Choice of the left side resulted in a 20% chance of getting a green stimulus, signaling 10 pellets of food, but an 80% chance of getting a red stimulus, signaling no food. Choice of the right side resulted in a 20% chance of getting a blue stimulus or an 80% chance of getting a yellow stimulus, each signaling three pellets of food (after [60]).