Inter-individual and age differences in exploration, neophobia and problem-solving ability in a Neotropical raptor (Milvago chimango)

Animal innovations have far-reaching ecological and evolutionary consequences. The occurrence and persistence of an innovation require several processes, including exploration, social and asocial learning, and low neophobia. In addition, the identity of the innovator may determine how these new behaviours are socially transmitted. Taking into account inter-individual and age differences, we investigated three correlates of animal innovation: object exploration, neophobia level and novel problem-solving ability in an opportunistic generalist raptor, the Chimango Caracara (Milvago chimango). Eighteen individuals (7 adults and 11 juveniles) were caught during the non-breeding period and housed in individual cages in outdoor aviaries. Each bird was given three tests: exploration, neophobia and problem-solving. Individuals differed in their response to novel situations both within and between age groups. Most of the juveniles were more explorative and had a lower neophobic response to a strange object than adult birds, but both age groups were able to solve a novel problem when given a food reward. In juveniles, neophobia level and problem-solving performance were inversely related; however, we found no relationship between these behaviours in adults. Exploration did not correlate with neophobia or problem-solving ability for either age group. This research is one of the few studies exploring the inter-individual and age differences in behavioural innovation and their correlates in a bird of prey. The explorative tendency, low neophobia and ability to innovate showed by M. chimango may be advantageous for this generalist and opportunistic raptor and might be some of the factors underlying its ecological success.     

Neophobia is negatively related to reversal learning ability in females of a generalist bird of prey,the Chimango Caracara, <Emphasis Type="Italic">Milvago chimango</Emphasis>

In an ever-changing environment, the ability to adapt choices to new conditions is essential for daily living and ultimately, for survival. Behavioural flexibility allows animals to maximise survival and reproduction in novel settings by adjusting their behaviour based on specific information and feedback acquired in their current environments. However, a growing body of evidence indicates that an individual’s personality type can limit the extent to which the individual might behave flexibly, by influencing the way an individual pays attention to novelty and how much information it collects and stores, which in turn affects the individual’s decision-making and learning process. In this study, the behavioural flexibility of a generalist predator, the Chimango Caracara, Milvago chimango, was analysed using the reversal learning paradigm, focusing on the comparison between age classes, and the relation of learning flexibility with a personality trait, the level of neophobia. Due to the low number of male individuals captured, this study was carried out only with female birds. The results showed that age had no significant effect either on the acquisition of a stimulus-reward association, or on the capacity of reversing this previously learned association. Reversal of the response was a harder task for these birds in comparison with the initial acquisition process. The individual’s performances in the learning tasks seemed to be uncorrelated with each other, suggesting that they involve different neural mechanisms. Contrary to the general pattern observed in the majority of previous work on personality and cognition in non-human animals, the level of neophobia did not correlate with the initial associative learning performance in both adults and juveniles, yet it showed a significant negative relationship with reversal learning ability, mainly in the regressive phase of this task, for the two age classes. Our results suggest that the predatory and generalist lifestyle of female individuals of M. chimango along with the selective pressures of the environment of the individuals studied might play a critical role in the degree and direction of the linkage between novelty response and learning flexibility observed in this study.     

Age differences in within-session habituation of exploratory behavior: effects of stimulus complexity

The effects of age on the habituation of exploratory behavior of 8-month- and 28-month-old male C57BL/NNia mice were examined under three different stimulus complexity conditions. Increases in the degree of stimulus complexity resulted in an attenuation of between-session habituation and an initial disruption of within-session habituation by 8-month-old mice. Although increases in stimulus complexity also resulted in an increase in the overall level of exploration by aged mice, stimulus complexity was not found to have a systematic effect on between- or within-session habituation by aged mice. No between-session habituation was observed in aged mice under any of the stimulus complexity conditions. Further, aged mice exhibited significant within-session increases, rather than decreases, in exploration under each stimulus complexity condition. This disruption of within-session habituation in aged mice was found to persist over four daily test sessions. In view of the specific patterns of exploration by aged mice, the disruption of within-session habituation was attributed to age-related differences in reactivity to the arousal-inducing properties of novel stimuli.     

Recognizing images: The role of motivational significance,complexity, social content,age, and gender

Memory for affective events plays an important role in determining people’s behavior and well-being. Its determinants are far from being completely understood. We investigated how recognition memory for affective pictures depends on pictures’ motivational significance (valence and arousal), complexity (figure-ground compositions vs. scenes), and social content (pictures with people vs. without people) and on observers’ age and gender. Younger, middle-aged, and older adults viewed 84 pictures depicting real-life situations. After a break, the participants viewed 72 pictures, half of which had been viewed previously and half of which were novel, and were asked to endorse whether each picture was novel or had been presented previously. Hits, false alarms, and overall performance (discrimination accuracy) were our dependent variables. The main findings were that, across participants, recognition memory was better for unpleasant than pleasant pictures and for pictures depicting people than pictures without people. Low-arousal pictures were more accurately recognized than high-arousal pictures, and this effect was significantly larger among middle-aged and older adults than younger adults. Recognition memory worsened across adulthood, and this decline was steeper among men than women. Middle-aged and older women outperformed their male counterparts. This study suggests that how well we are able to successfully discriminate previously seen pictorial stimuli from novel stimuli depends on several pictures’ properties related to their motivational significance and content, and on observer’s age and gender.     

Looking time: The effects of stimulus complexity and familiarity

During a 10 min. stimulus familiarization period, three groups of 60 Ss each received either 0, 10, or 20 sec. of familiarization on each of 30 experimental stimuli: 10 each of low, medium, and high stimulus complexity. All Ss then viewed the experimental stimuli in a second task, during which they could look at each stimulus for as long as they wished (free looking). For half the Ss in each group, free looking was administered immediately after the familiarization period. The remaining Ss received free looking 48 hr. later. The results replicated earlier research which has shown that free looking time is inversely related to stimulus familiarity, and directly related to stimulus complexity. Unlike earlier findings, the data suggested that with a 48 hr. delay between familiarization and free looking, a stimulus can, at least partially, recover from the decrement in looking time produced by 10 sec. of familiarization.     

The role of social pressure,attention to the stimulus,and self-doubt in conformity

The theorizing of Asch and Moscovici was used as a framework for exploring the relationships among social pressure, attention to the stimulus, doubt about one's own judgment, and conformity. Male and female subjects (N = 185) were confronted either with one (low social pressure) or three (high social pressure) others who judged 12 critical pairs of noises as equal in loudness. The noises within each pair actually varied in how similar they were in loudness. High social pressure resulted in most subjects paying either little or much attention to the stimulus; low social pressure resulted in most subjects paying a moderate amount of attention to the stimulus. When social pressure was high, greater self-doubt was associated with less attention to the stimulus; when social pressure was low, greater self-doubt was associated with more attention to the stimulus. Conformity was positively associated with self-doubt and negatively associated with attention to the stimulus. Social pressure increased conformity, particularly when subjects paid little attention to the stimulus. Although the results are interpreted as partially consistent with both the Asch and the Moscovici perspectives, they are not totally consistent with either.     

Statistical learning in typically developing children: the role of age and speed of stimulus presentation

It is possible that statistical learning (SL) plays a role in almost every mental activity. Indeed, research on SL has grown rapidly over recent decades in an effort to better understand perception and cognition. Yet, there remain gaps in our understanding of how SL operates, in particular with regard to its (im)mutability. Here, we investigated whether participant-related variables (such as age) and task-related variables (such as speed of stimulus presentation) affect visual statistical learning (VSL) in typically developing children. We tested 183 participants ranging in age from 5 to 12 years and compared three speeds of presentation (using stimulus durations of 800, 400 and 200 msecs). A multiple regression analysis revealed significant effects of both age and speed of presentation - after attention during familiarization and gender had been taken into consideration. VSL followed a developmental trajectory whereby learning increased with age. The amount of learning increased with longer presentation times (as shown by Turk-Browne, Jungé & Scholl, 2005, in their study of adults). There was no significant interaction between the two variables. These findings assist in elucidating the nature of statistical learning itself. While statistical learning can be observed in very young children and at remarkably fast presentation times, participant- and task-related variables do impact upon this type of learning. The findings reported here may serve to enhance our understanding of individual differences in the cognitive and perceptual processes that are thought to rely, at least in part, on SL (e.g. language processing and object recognition).     

The influence of novelty and complexity on exploratory behavior in 12-month-old infants

This study investigated the influence of the novelty of the environment and the novelty and complexity of the objects (toys) it contained on the exploratory behavior of 12-month-old infants. Each infant was given a choice between novel and familiar toys located in two adjacent rooms (toy rooms). The novelty of the objects was manipulated by allowing the infants to play with one set of toys during a 5-min familiarization trial prior to the choice trial. The novetly of the environment was manipulated by allowing some infants to see, enter, and remain in the toy rooms during the familiarization trial. Finally, the complexity of the objects was manipulated by varying the number of familiar and novel toys; some Ss had four toys in each set (complex array) and some had only one (simple array). The results indicate that all three factors influenced the infants' exploratory behavior. Ss first approached, and spent more time manipulating, the novel than the familiar toys; they spent more time in the toy rooms if they were novel; and they spent more time manipulating the complex array of toys than the simple array.     

Fast times and easy questions: the effects of age,experience and question complexity on web survey response times

This paper examines response times (RT) to survey questions. Cognitive psychologists have long relied on response times to study cognitive processes but response time data have only recently received attention from survey researchers. To date, most of the studies on response times in surveys have treated response times either as a predictor or as a proxy measure for some other variable (e.g. attitude accessibility) of greater interest. As a result, response times have not been the main focus of the research. Focusing on the nature and determinants of response times, this paper examines variables that affect how long it takes respondents to answer questions in web surveys. Using the survey response model proposed by Tourangeau, Rips, and Rasinski (2000), we include both item‐level characteristics and respondent‐level characteristics thought to affect response times in a two‐level cross‐classified model. Much of the time spent on processing the questions involves reading and interpreting them. The results from the cross‐classified models indicate that response times are affected by question characteristics such as the total number of clauses and the number of words per clause that probably reflect reading times. In addition, response times are also affected by the number and type of answer categories, and the location of the question within the questionnaire, as well as respondent characteristics such as age, education and experience with the Internet and with completing web surveys. Aside from their fixed effects on response times, respondent‐level characteristics (such as age) are shown to vary randomly over questions and effects of question‐level characteristics (such as types of questions and response scales) vary randomly over respondents. Copyright © 2007 John Wiley & Sons, Ltd.     

Prototypes in category learning: the effects of category size, category structure, and stimulus complexity

Although research in categorization has sometimes been motivated by prototype theory, recent studies have favored exemplar theory. However, some of these studies focused on small, poorly differentiated categories composed of simple, 4-dimensional stimuli. Some analyzed the aggregate data of entire groups. Some compared powerful multiplicative exemplar models to less powerful additive prototype models. Here, comparable prototype and exemplar models were fit to individual-participant data in 4 experiments that sampled category sets varying in size, level of category structure, and stimulus complexity (dimensionality). The prototype model always fit the observed data better than the exemplar model did. Prototype-based processes seemed especially relevant when participants learned categories that were larger or contained more complex stimuli.