Discrimination of individual vocalizations by black-capped chickadees (Poecile atricapilla)

The auditory perceptual abilities of male black-capped chickadees (Poecile atricapilla) were examined using an operant go/no-go discrimination among 16 individual vocalizations recorded at 5 m. The birds learned to discriminate about equally well among eight male chickadee fee-bee songs and eight female zebra finch (Taeniopygia guttata) distance calls. These results do not indicate that chickadees have a species-specific advantage in individual recognition for conspecific over heterospecific vocalizations. We then transferred the chickadees to a discrimination of the same songs and calls rerecorded at a moderate distance. These results showed accurate transfer of discrimination from 16 vocalizations recorded at 5 m to novel versions of the same 16 songs and calls rerecorded at 25 m. That is, chickadees recognized individual songs and calls despite degradation produced by rerecording at 25 m. Identifying individual vocalizations despite their transformation by distance cues is here described as a biologically important example of perceptual constancy.     

Proactive interference, recency, and associative strength: Comparisons of black-capped chickadees and dark-eyed juncos

Black-capped chickadees (Parus atricapillus) and dark-eyed juncos (Junco hyemalis) were required to match to the last item from a series of up to three stimuli differing in both location and color. When rewarded for pecking the target stimulus during the study phase of each series, black-capped chickadees demonstrated proactive interference (PI) from stimuli presented prior to the target, whereas juncos did not. When they made an error, chickadees were more likely than were juncos to choose a distractor from the study series rather than a novel stimulus. When reward was no longer associated with presentation of the final target sample in a series, juncos also suffered PI. These results indicate that chickadees and juncos differ in the degree to which the recency of stimuli and the associative strength of stimuli control correct matching.     

Spatial configuration and list learning of proximally cued arms by rats in the enclosed four-arm radial maze

In an enclosed four-arm radial maze, after sampling three experimenter-selected baited arms (thestudy segment) and following rotation of the maze, rats had to find the fourth baited arm among all four unblocked arms (test segment). The rats learned this task with two sets of arm cues, objects at arms’ entrances and full arm inserts, each maintained in a fixed configuration. When we changed the configuration of one set of arms to itsmirror image and that of the other set to a moremixed variation by switching opposite and adjacent cued arms, the rats’ accuracy was similarly disrupted (Experiment 1). In Experiment 2, the same rats rapidly recovered their high search accuracy on four new configurations recombined from pairs of adjacent arms and pairs of opposite cued arms from the previous final two configurations. Their test segment search accuracy, however, was again disrupted when these configurations were varied either only over trials’ study segments or only over trials’ test segments. In Experiment 3, however, these rats attained accuracy as high on two sets of cued arms with constantly changing configurations as on two sets with constant configurations. Thus, the rats were able to separately represent four different spatially stable configurations, and then they could learn to represent two of these configurations as lists of spatially irrelevant items. We discuss these findings in terms of association theory and parallel map theory (Jacobs & Schenk, 2003).     

Spatial pattern learning in the radial arm maze

Rats experienced a spatial pattern of baited and unbaited arms in an eight-arm radial maze. The spatial pattern remained constant over trials, but the spatial locations that were baited varied unpredictably. Although there was no evidence of control by the spatial pattern during free choice training trials, the rats’ ability to locate baited arms in forced choice test trials was superior to that of animals in a control condition for which maze arms were not baited in a consistent spatial pattern. This is consistent with the results of experiments showing that spatial choices by rats in a pole box maze are controlled by abstract spatial patterns.     

Comparing cognition by integrating concept learning,proactive interference,and list memory

This article describes an approach for training a variety of species to learn the abstract concept of same/different, which in turn forms the basis for testing proactive interference and list memory. The stimulus set for concept-learning training was progressively doubled from 8, 16, 32, 64, 128 . . . to 1,024 different pictures with novel-stimulus transfer following learning. All species fully learned the same/different abstract concept: capuchin and rhesus monkeys learned more readily than pigeons; nutcrackers and magpies were at least equivalent to monkeys and transferred somewhat better following initial training sets. A similar task using the 1,024-picture set plus delays was used to test proactive interference on occasional trials. Pigeons revealed greater interference with 10-s than with 1-s delays, whereas delay time had no effect on rhesus monkeys, suggesting that the monkeys’ interference was event based. This same single-item same/different task was expanded to a 4-item list memory task to test animal list memory. Humans were tested similarly with lists of kaleidoscope pictures. Delays between the list and test were manipulated, resulting in strong initial recency effects (i.e., strong 4th-item memory) at short delays and changing to a strong primacy effect (i.e., strong 1st-item memory) at long delays (pigeons 0-s to 10-s delays; monkeys 0-s to 30-s delays; humans 0-s to 100-s delays). Results and findings are discussed in terms of these species’ cognition and memory comparisons, evolutionary implications, and future directions for testing other species in these synergistically related tasks.     

Spatial learning by rats across visually disconnected environments

Experiments were designed in which some properties of spatial representations in rats could be examined. Adult subjects were trained to escape through a hole at a fixed position in a large circular arena (see Schenk, 1989). The experiments were conducted in the dark, with a limited number of controlled visual light cues, in order to assess the minimal cue requirement for place learning. Three light cues identical in shape, height, and distance from the table were used. Depending on the condition, they were either permanently on or alternatively on or off, contingent on the position of the rat in the field. Two questions were asked: (1) How many identical visual cues were necessary for spatial discrimination in the dark, and (2) could rats integrate the relative positions of separate cues, under conditions in which the rat was never allowed to perceive all three cues simultaneously. The results suggest that rats are able to achieve a place discrimination task even if the three cues necessary for efficient orientation can never be seen simultaneously. A dissociation between the discrimination of the spatial position of the goal and the capacity to reach it by a direct path suggests that, with a reduced number of cues, prolonged locomotion might be required for accurate orientation in the environment.     

Spatial pattern learning in rats: Conditional control by two patterns

Rats searched for food hidden on top of poles in a 4 × 4 matrix of poles. Before each trial, the location of the four baited poles was unpredictable. However, the poles were always baited in one of two spatial patterns, either a square or a line. The food hidden on the four baited poles was one of two types, and the food type determined the identity of the pattern. Thus, once one baited pole was discovered, the food type provided a cue for the spatial pattern in which the remaining food was hidden. The results showed that rats learned the two spatial patterns in which the food was hidden and used the conditional cue to determine which pattern was relevant on individual trials, thereby increasing the efficiency of spatial search.     

“濒危”世界遗产名单又添新成员

第31届联合国世界遗产大会决定,将厄瓜多尔的加拉帕戈斯群岛和塞内加尔的尼奥科洛科巴国家公园列入“濒危”世界遗产名单。     

关于链表结构程序中的代码冗余问题

通过对链表结构内部成员变量作用的分析，从中抽象出用于链表连接的指针结构，并利用这个指针结构构造出链表基本操作的通用函数，减少冗余代码，提高软件代码的独立性、可读性和执行效率。     

Towards a sight word list in Arabic

While the English language boasts a century of research into its most frequently-used words, no such attempt has ever formally been made in the Arab world. This pioneering study presents a list of 500 commonly-used words in the Arabic language based on compilations of words gathered from a number of popular reading series in Lebanon, spanning grades K to 3. This list can serve as a powerful tool for language teachers—who face several challenges posed by the inherent nature of Arabic in terms of diglossia, orthography and morphology—and provide them with a handy list of words for their pupils. The study has its limitations in terms of scope, breadth and the nature of the technology used for counting words. Nonetheless, it makes a number of recommendations for the future, including the development of a readability formula based on this list, the expansion of the scope of this word list and improvement to increase its technical accuracy.     

Spatial abilities in an elective course of applied anatomy after a problem‐based learning curriculum

A concern on the level of anatomy knowledge reached after a problem‐based learning curriculum has been documented in the literature. Spatial anatomy, arguably the highest level in anatomy knowledge, has been related to spatial abilities. Our first objective was to test the hypothesis that residents are interested in a course of applied anatomy after a problem‐based learning curriculum. Our second objective was to test the hypothesis that the interest of residents is driven by innate higher spatial abilities. Fifty‐nine residents were invited to take an elective applied anatomy course in a prospective study. Spatial abilities were measured with a redrawn Vandenberg and Kuse Mental Rotations Test in two (MRT A) and three (MRT C) dimensions. A need for a greater knowledge in anatomy was expressed by 25 residents after a problem‐based learning curriculum. MRT A and C scores obtained by those choosing (n = 25) and not choosing (n = 34) applied anatomy was not different (P = 0.46 and P = 0.38, respectively). Percentage of residents in each residency program choosing applied anatomy was different [23 vs. 31 vs. 100 vs. 100% in Family Medicine, Internal Medicine, Surgery, and Anesthesia, respectively; P < 0.0001]. The interest of residents in applied anatomy was not driven by innate higher spatial abilities. Our applied anatomy course was chosen by many residents because of training needs rather than innate spatial abilities. Future research will need to assess the relationship of individual differences in spatial abilities to learning spatial anatomy. Anat Sci Ed 2:107–112, 2009. © 2009 American Association of Anatomists.