Using source cues and familiarity cues to resist imagination inflation

To investigate whether people can resist imagination inflation--the imagination-induced increased confidence that fictitious childhood events really happened--we gave them different types of cues. In a three-stage procedure, participants: (1) rated their confidence that a list of childhood events had happened to them, (2) imagined some of these events, and (3) made confidence ratings a second time. Subjects received either no cues about the source of the imagined event, an additional source cue (perspective), an additional familiarity cue (a plausibility questionnaire), or both cues. Only subjects who had both types of cues resisted imagination inflation. These results suggest that additional cues can sometimes safeguard people from becoming more confident that fictitious events were genuine experiences.     

Cattle discriminate between familiar and unfamiliar conspecifics by using only head visual cues

Faces have features characteristic of the identity, age and sex of an individual. In the context of social communication and social recognition in various animal species, facial information is relevant for discriminating between familiar and unfamiliar individuals. Here, we present two experiments aimed at testing the ability of cattle (Bos taurus) to visually discriminate between heads (including face views) of familiar and unfamiliar conspecifics represented as 2D images. In the first experiment, we observed the spontaneous behaviour of heifers when images of familiar and unfamiliar conspecifics were simultaneously presented. Our results show that heifers were more attracted towards the image of a familiar conspecific (i.e., it was chosen first, explored more, and given more attention) than towards the image of an unfamiliar one. In the second experiment, the ability to discriminate between images of familiar and unfamiliar conspecifics was tested using a food-rewarded instrumental conditioning procedure. Eight out of the nine heifers succeeded in discriminating between images of familiar and unfamiliar conspecifics and in generalizing on the first trial to a new pair of images of familiar and unfamiliar conspecifics, suggesting a categorization process of familiar versus unfamiliar conspecifics in cattle. Results of the first experiment and the observation of ear postures during the learning process, which was used as an index of the emotional state, provided information on picture processing in cattle and lead us to conclude that images of conspecifics were treated as representations of real individuals.     

Novelty and familiarity as redundant cues in retardate discrimination learning.

Forty retarded children, a Low Mental Age (MA) Group (mean MA 3-3 yrs.) and a High MA Group (mean MA 5–7 yrs.) were trained on 120 different two-choice visual discrimination problems. For all subjects, half of these problems were standard four-trial problems (Standard Condition). The remaining 60 problems were variants of the Moss-Harlow Design, the first trial differing from the initial two-choice trial of the Standard Condition in having only a single stimulus present, either the positive stimulus (Positive Condition) or the negative stimulus (Negative Condition), in both cases followed by three trials with both stimuli present. Each subject received either Positive Condition Problems or Negative Condition Problems, but not both. An analysis of Trial 2 performance revealed that although no interproblem changes in the Standard Condition occurred, there were large initial performance differences and large interproblem changes in the Positive and Negative Conditions which varied with MA. Initial performance differences were interpreted as a differential preference for novel and familiar stimuli in the two MA Groups. Changes in interproblem performance were consistent with the hypothesis that these MA dependent novelty-familiarity preferences could be influenced by novelty-familiarity redundancy training. These interpretations were supported by predictions from theory.     

Memory for details about people: familiarity,relatedness, and gender congruency

This study examines factors that influence memory for details about people. In two experiments, subjects learned fictitious details about familiar (friends, relatives) and/or unfamiliar individuals, and were tested both immediately and after a 1-week delay. To control for a confounding between familiarity and genetic relatedness in Experiment 1, in Experiment 2 specific relationships (identical twin, first cousin, acquaintance) were assigned to unfamiliar individuals. Across experiments, retention was enhanced for familiar compared to unfamiliar individuals, for friends/acquaintances compared to relatives, for more closely than distantly related individuals, and for individuals of the opposite gender as the subject.     

Verbal versus olfactory cues: affect in elicited memories

Verbal processing has a reduced role for olfactory stimuli. It is difficult to provide a label for an odor experience. Odor perception can retrieve memories of life events with personal meaning and elicit affective experiences. Odors that have emotionally loaded content could produce older memories. Common odors with well-known names have been used. In Exp. 1 the names were shown, and the subjects were asked to imagine the corresponding odors; subsequently those odorants were presented. In Exp. 2 at first the odorants were presented and subsequently their names, printed one each per white card. The subjects were requested to provide written free associations. At the end of each session they scored a semantic differential. The hypothesis that emotionally loaded associations are more frequent when evoked by odorants seems confirmed, supported also by some reliable differences between the profiles for olfactory verbal stimuli. The evaluation of olfactory stimuli did not differ from one experiment to the other; verbal stimuli, on the contrary, are differently evaluated if the corresponding odorants were presented before or after their labels.     

Discrimination of auditory intensities by rats

Rats were trained to press one of two keys when a standard intensity value of a 4.0-kHz sine tone (70 or 100 db re 2 x 10(-4) microbar) was presented from a centrally located loudspeaker. Pressing the other key was reinforced when comparison intensity values (as much as 30 db less than the standard value) were presented. The animals initiated tone presentations by breaking a light beam at the rear of the chamber. Correct choices produced brain-stimulation reinforcement, and errors produced a timeout. A procedure designed by Jenkins was used to partial out choice data under potential control of sequential cues in the stimulus series. When the standard-comparison intensity difference was varied, the rats showed similar psychometric functions despite wide differences in response bias (relative position preference). A signal detection analysis showed that response biases for individual animals remained fairly consistent during psychophysical testing. The trend of decreasing choice accuracy at small intensity differences was described by the cumulative normal probability function. The similarity of psychometric functions obtained with 70- and 100-db standards supported Weber's law. There was some evidence that response latencies were controlled by intensity differences even when choice behavior was undifferentiated.     

Discrimination of checkerboard patterns by rats

Fifteen rats were trained to discriminate between a regular checkerboard pattern and a similar pattern containing a “mistake.” The animals subsequently transferred to many other pairs of regular and irregular patterns differing widely from the originals. The results suggest that rats can induce and store highly abstract rules describing input patterns.     

Maternal aggression in mice and rats towards male and female conspecifics

Although postpartum aggression is primarily studied in laboratory mice and rats, it is unclear how the two species compare in terms of the factors associated with peak levels of aggressive behavior. Using the same experimental protocol, we assessed the relative effect of intruder sex and time since parturition on the frequency of maternal aggression in Long-Evans rats and CFW mice. Females were studied for 2 consecutive cycles of pregnancy and lactation. During the first lactation, aggression was tested 2 times per week for 3 weeks in order to select animals that attacked at least once. During the second lactation, both pup care and aggressive behavior were assessed in detail. Testing occurred twice in each lactation week, with postpartum days 1–7, 8–14, and 15–21 considered weeks 1, 2, and 3, respectively. Maternal behavior towards 3 pups was observed for 5 minutes, followed by a confrontation with an intruder. Lactating females encountered female intruders once per week, and male intruders in the alternate weekly test. The same behaviors were measured in the 2 species, except for the tail rattle exhibited by mice and the aggressive posture shown by rats. Lactating rats and mice show similar decreases in pup care behavior as lactation progresses in time; yet the factors associated with peak levels of aggression differ between species. In Long-Evans rats, female intruders receive more attacks, threats, and aggressive postures than males. Frequency of attack bite and sideways threat declines in each passing week of lactation. Lactating mice are more aggressive toward male intruders throughout the lactation period. Mice still attack and threaten during the third week of lactation, but less often in comparison to the first week. Therefore, peak levels of aggression vary in mice and rats both as a function of intruder sex and lactation week.     

Context-dependent use of olfactory cues by foragers of Vespula germanica social wasps

Animal Cognition - Food search is guided by cues from different sensory modalities, such as olfactory and visual. In social wasps, olfaction plays a key role in locating new resources. However,...     

The role of sparsely distributed representations in familiarity recognition of verbal and olfactory materials

We present the generalized signal detection theory (GSDT), where familiarity is described by a sparse binomial distribution of binary node activity rather than by normal distribution of familiarity. Items are presented in a distributed representation, where each node receives either noise only, or signal and noise. An old response (i.e., a “yes” response) is made if at least one node receives signal plus noise that is larger than the activation threshold, and item variability is determined by the distribution of activated nodes as the threshold is varied. A distinct representation leads to better performance and a lower ratio of new to old item variability, than a more distributed and less distinct representations. Here we apply the GSDT to empirical data on verbal and olfactory memory and suggest that verbal memory relies on a distinct neural item representation, whereas olfactory memory has a fuzzy neural representation leading to poorer memory and inducing a larger ratio of new to old item variability.     

The effects of inversion and familiarity on face versus body cues to person recognition

Extensive research has focused on face recognition, and much is known about this topic. However, much of this work seems to be based on an assumption that faces are the most important aspect of person recognition. Here we test this assumption in two experiments. We show that when viewers are forced to choose, they do use the face more than the body, both for familiar (trained) person recognition and for unfamiliar person matching. However, we also show that headless bodies are recognized and matched with very high accuracy. We further show that processing style may be similar for faces and bodies, with inversion effects found in all cases (bodies with heads, faces alone and bodies alone), and evidence that mismatching bodies and heads causes interference. We suggest that recent findings of no inversion effect when stimuli are headless bodies may have been obtained because the stimuli led viewers to focus on nonbody aspects (e.g., clothes) or because pose and identity tasks led to somewhat different processing. Our results are consistent with holistic processing for bodies as well as faces. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

The use of olfactory cues in solving a visual discrimination task

Albino rats, trained in a miniaturized WGTA, were found to learn an olfactory discrimination despite the fact that visual cues were relevant and obvious. The results provide a further warning against the use of macrosmatic animals in visual discrimination tasks in which olfactory cues may be relevant.     

Discrimination learning during the first year: stimulus and positional cues

In four studies, 3-, 6-, and 9-month-old human infants were tested in a discrimination learning task in which visual fixation to a particular stimulus or lateral position was reinforced with an auditory stimulus. In Experiment 1, all age groups exhibited acquisition, extinction, and reinstatement of fixation to the reinforced target or position. Experiment 2 revealed that 3-month-olds retained the positional discrimination but not the stimulus discrimination after a 5-min delay between acquisition and extinction; older infants retained both types of discriminations. In Experiments 3 and 4 we investigated a possible developmental shift in the dominance of positional versus stimulus cues by training infants on displays in which stimulus and position were confounded and then by dissociating the cues on test trials. Results from both experiments indicated positional cue dominance for young infants and stimulus cue dominance for older infants. The findings are discussed in terms of differences in the attentional demands elicited by proprioceptive versus exteroceptive cues.     

Effect of training and familiarity on responsiveness to human cues in domestic dogs (Canis familiaris)

Domestic dogs (Canis familiaris) seem to possess an evolved competency to follow human-given cues, often out-performing their wild progenitor the wolf (Canis lupus) on cue-following tasks. However, domestication may not be solely responsible for the socio-cognitive skills of dogs, with ontogenetic experience also playing a role. This research evaluated the effects of intensive training on cue-following behaviour using an unreinforced object-choice paradigm. The responses of dogs that were trained to competitive levels were compared to those of pet dogs with only basic training, and dogs living in an animal shelter that demonstrated no or only rudimentary following of basic commands. Using a cue-following task where three types of cues were presented by familiar and unfamiliar human partners, the number of cues followed by each training group were recorded. All dogs found cues where gesture was combined with a congruent head and eye movement easier to follow than either gesture or eye gaze alone. Whether the cue-giver was familiar or not had a significant effect on number of cues followed in homed dogs, and the performance of shelter dogs was comparable to the other groups when faced with an unfamiliar cue-giver. Contrary to predictions, level of training did not improve performance on the cue-following task. This work does provide support for the presence of an evolved adaptation to exploit social cues provided by humans that can be augmented by familiarity with the cue giver. However, additional joint activity as experienced in an intensive training regime does not seem to increase accuracy in following human-given cues.     

False recognition across meaning,language, and stimulus format: Conceptual relatedness and the feeling of familiarity

Four experiments examined contributions of conceptual relatedness and feelings of familiarity to false recognition. Participants first studied lists of unrelated items (e.g., table, lock) followed by a recognition test with three types of items: (1) studied items (e.g., table), (2) semantically related lures (e.g., key), and (3) unrelated lures (e.g., cup). Participants falsely recognized more related than unrelated lures when the stimuli were words (Experiment 1A) and pictures (Experiment 1B), when the studied items and related lures differed in language (Experiment 2), and when they differed in perceptual format (Experiment 3). In Experiment 4, an attribution manipulation, designed to make feelings of familiarity nondiagnostic for memory judgments, eliminated the false-recognition effect obtained in Experiment 3. Overall, the study suggests that conceptual relatedness produces false recognition even in the absence of shared perceptual surface features between study and test items, and it does so by generating feelings of familiarity.     

The use of prosodic cues in language discrimination tasks by rats

Recent research with cotton-top tamarin monkeys has revealed language discrimination abilities similar to those found in human infants, demonstrating that these perceptual abilities are not unique to humans but are also present in non-human primates. Specifically, tamarins could discriminate forward but not backward sentences of Dutch from Japanese, using both natural and synthesized utterances. The present study was designed as a conceptual replication of the work on tamarins. Results show that rats trained in a discrimination learning task readily discriminate forward, but not backward sentences of Dutch from Japanese; the results are particularly robust for synthetic utterances, a pattern that shows greater parallels with newborns than with tamarins. Our results extend the claims made in the research with tamarins that the capacity to discriminate languages from different rhythmic classes depends on general perceptual abilities that evolved at least as far back as the rodents. Electronic Publication