Eurasian jays predict the food preferences of their mates

The cognitive abilities of animals continue to fascinate both scientists and nonscientists. Although the abilities of the primates, our closest living relatives, generally attract most interest, several different lines of research have demonstrated high levels of intellectual capacity in birds, particularly corvids. The members of this family are known for their large brains and have performed well in many cognitive tasks using different paradigms (1–3). This finding has led to substantial revision of thinking about avian intelligence, including the suggestion of convergence in the evolution of cognitive abilities between corvids and primates (4). In PNAS, Ostojić et al. (5) add significantly to this literature with a very elegant experiment demonstrating the ability of male European jays (Garrulus glandarius) to predict the feeding preferences of their mates. The study is significant for many reasons: it demonstrates a high and unexpected level of flexibility, reports results bearing strong resemblance to human stateattribution and further confirms the importance of studying cooperative as well as competitive situations

Searching image in blue jays: Facilitation and interference in sequential priming

Repeated exposure to a single target type (sequential priming) during visual search for multiple cryptic targets commonly improves performance on subsequent presentations of that target. It appears to be an attentional phenomenon, a component of the searching image effect. It has been argued, however, that if searching image is an attentional process, sequential priming should also interfere with performance on subsequent nonprimed targets, and such interference has never been unequivocally demonstrated. In blue jays (Cyanocitta cristata) searching in an operant apparatus for targets derived from images of cryptic moths, detection performance was strongly facilitated in the course of a sequential prime but was relatively unaffected by sequences of mixed target types. Detection accuracy in subsequent probe trials was enhanced by priming with targets of the same type, whereas accuracy on cryptic probes following priming with a more conspicuous target was significantly degraded. The results support an attentional interpretation of searching image

Diet Choices of Blue Jays (Cyanocitta cristata) as a Function of Time Spent Foraging

Optimal diet theory predicts choices among prey types. With sequential prey encounters, less profitable prey types may be rejected immediately because rejecting the prey item at hand increases the probability of encountering more profitable types. However, Lucas (1985) argued that at the end of a foraging bout, all encountered prey types should be accepted because the opportunity to encounter more profitable types is limited. We tested Lucas’s prediction in a simulation, allowing blue jays to hunt for two moth types differing in profitability. During the last min of both 10- and 20-min foraging bouts, the less profitable type was attacked more often than during the middle of the bouts; this is an end-of-the-bout effect. The less profitable type was also attacked more often at the beginning of the bouts; this is probably a sampling effect. Jays appear to integrate information about time spent foraging with information about relative prey profitability

Interference Effects in the Memory for Serially Presented Locations in Clark’s Nutcrackers, Nucifraga columbiana

The authors tested the spatial memory of serially presented locations in Clark’s nutcrackers (Nucifraga columbiana). Birds were serially presented with locations in an open room. The authors buried a seed in a sand-filled cup at each location and then tested nutcrackers for their memory for each location in the list by using the cluster method. For each item in the list, the authors opened a cluster of 6 holes. Accuracy was measured by how many tries were required for the bird to find the correct location within each cluster. In Experiments 1 and 2, the authors presented 2 lists of locations and found evidence for proactive and retroactive interference. Nutcrackers made errors by visiting the interfering list of locations during recovery of the target list. This finding demonstrates that nutcrackers are susceptible to proactive and retroactive interference during the recall of spatial information

Diet Choices of Blue Jays (Cyanocitta cristata) as a Function of Time Spent Foraging

Optimal diet theory predicts choices among prey types. With sequential prey encounters, less profitable prey types may be rejected immediately because rejecting the prey item at hand increases the probability of encountering more profitable types. However, Lucas (1985) argued that at the end of a foraging bout, all encountered prey types should be accepted because the opportunity to encounter more profitable types is limited. We tested Lucas’s prediction in a simulation, allowing blue jays to hunt for two moth types differing in profitability. During the last min of both 10- and 20-min foraging bouts, the less profitable type was attacked more often than during the middle of the bouts; this is an end-of-the-bout effect. The less profitable type was also attacked more often at the beginning of the bouts; this is probably a sampling effect. Jays appear to integrate information about time spent foraging with information about relative prey profitability

Intraproblem retention during learning-set acquisition in bluejays (Cyanocitta eristata)

Recent experiments have shown that bluejays and rhesus monkeys experienced in object-discrimination learning set (ODLS) exhibit a rapid decline in performance when a retention interval is inserted between successive trials of individual ODLS problems (Bessemer & Stollnitz, 1971; Kamil, Lougee, & Shulman, 1973). This intraproblem retention loss (IRL), or forgetting, has been interpreted as reflecting the importance of relatively transient memory traces for events of previous trials of the ODLS problem as determinants of choice behavior on the current trial of the same problem. According to this model, these memory traces function as discriminative stimuli in a conditional discrimination which controls choice behavior in the sophisticated subject. For example, if the subject remembers having responded to Object x, and having been rewarded on the previous trial(s), then he approaches Object x on the next trial; however, if he remembers nonreward, then he avoids Object x. This model is obviously similar to the win-stay, lose-shift hypothesis proposed by Levine (1959), but would seem to have two advantages. First, it specifies the stimuli, specific memory traces of previous trial events, necessary for hypothesis behavior to occur. Second, it explains the finding of rapid IRL if we assume that these memory traces are transient, losing strength during retention intervals

Visual Search and Attention in Blue Jays (\u3ci\u3eCyanocitta cristata\u3c/i\u3e): Associative Cuing and Sequential Priming

Visual search for complex natural targets requires focal attention, either cued by predictive stimulus associations or primed by a representation of the most recently detected target. Because both processes can focus visual attention, cuing and priming were compared in an operant search task to evaluate their relative impacts on performance and to determine the nature of their interaction in combined treatments. Blue jays were trained to search for pairs of alternative targets among distractors. Informative or ambiguous color cues were provided before each trial, and targets were presented either in homogeneous blocked sequences or in constrained random order. Initial task acquisition was facilitated by priming in general, but was significantly retarded when targets were both cued and primed, indicating that the two processes interfered with each other during training. At asymptote, attentional effects were manifested mainly in inhibition, increasing latency in miscued trials and decreasing accuracy on primed trials following an unexpected target switch. A combination of cuing and priming was found to interfere with performance in such unexpected trials, apparently a result of the limited capacity of working memory. Because the ecological factors that promote priming or cuing are rather disparate, it is not clear whether they ever simultaneously contribute to natural predatory search

Changing Room Cues Reduces the Effects of Proactive Interference in Clark’s Nutcrackers, \u3ci\u3eNucifraga columbiana\u3c/i\u3e

To determine what factors are important for minimizing interference effects in spatial memory, Clark’s Nutcrackers, Nucifraga columbiana were tested for their spatial memory for two serial lists of locations per day. In this experiment two unique landmark sets were either different between List 1 and List 2 or the same. We found that Nutcrackers were most susceptible to interference when the landmark sets were the same. This study suggests that repeatedly testing animal memory in the same room, with the same cues, can hamper recall due to interference

Do Clark’s nutcrackers demonstrate what-where-when memory on a cache-recovery task?

What-where-when (WWW) memory during cache recovery was investigated in six Clark’s nutcrackers. During caching, both red- and blue-colored pine seeds were cached by the birds in holes filled with sand. Either a short (3 day) retention interval (RI) or a long (9 day) RI was followed by a recovery session during which caches were replaced with either a single seed or wooden bead depending upon the color of the cache and length of the retention interval. Knowledge of what was in the cache (seed or bead), where it was located, and when the cache had been made (3 or 9 days ago) were the three WWW memory components under investigation. Birds recovered items (bead or seed) at above chance levels, demonstrating accurate spatial memory. They also recovered seeds more than beads after the long RI, but not after the short RI, when they recovered seeds and beads equally often. The differential recovery after the long RI demonstrates that nutcrackers may have the capacity for WWW memory during this task, but it is not clear why it was influenced by RI duration