Quantification abilities in angelfish (Pterophyllum scalare): the influence of continuous variables

Previous studies investigating quantity discrimination have shown that angelfish are able to select the larger of two groups of conspecifics (shoals). The discrimination limits shown by angelfish were similar to those found for other vertebrates when large (≥4) and small quantities (<4) were presented. However, in these studies, no attempt was made to control for non-numerical features of the stimulus shoals and thus the question whether numerical or some quantitative attributes of the shoals were utilized for making the choices could not be answered. Here, we investigate whether angelfish can discriminate between shoals differing in numerical size using non-numerical attributes. We systematically manipulate density, inter-fish distance, and overall space occupied by the shoals, one factor at a time, and analyse the choices angelfish made between the contrasting stimulus shoals. The stimulus shoals consisted of contrasts between large (10 vs. 5) and small (3 vs. 2) number of conspecifics. We found density to be a sufficient condition for discrimination between large shoals as the test subjects preferred the more dense shoal. Manipulation of inter-fish distance indicated that this variable is not a necessary factor in discrimination at either shoal size contrast. Likewise, we found that the size of space occupied by the contrasted shoals also did not significantly influence discrimination. Sensitivity to the density of large shoals indicates that angelfish can discriminate shoal size using this non-numerical cue. Nevertheless, the factors we examined may represent only a subset of all possible non-numerical features upon which angelfish may base their discrimination. Thus, we suggest that further research is required to clarify whether and under what circumstances angelfish may use numerical or non-numerical features when discriminating between shoals of differing size.     

Quantity discrimination in angelfish (<Emphasis Type="Italic">Pterophyllum scalare</Emphasis>) is maintained after a 30-s retention interval in the large but not in the small number range

The ability to discriminate between sets that differ in the number of elements can be useful in different contexts and may have survival and fitness consequences. As such, numerical/quantity discrimination has been demonstrated in a diversity of animal species. In the laboratory, this ability has been analyzed, for example, using binary choice tests. Furthermore, when the different number of items first presented to the subjects are subsequently obscured, i.e., are not visible at the moment of making a choice, the task requires memory for the size of the sets. In previous work, angelfish (Pterophyllum scalare) have been found to be able to discriminate shoals differing in the number of shoal members both in the small (less than 4) and the large (4 or more) number range, and they were able to perform well even when a short memory retention interval (2–15 s) was imposed. In the current study, we increased the retention interval to 30 s during which the shoals to choose between were obscured, and investigated whether angelfish could show preference for the larger shoal they saw before this interval. Subjects were faced with a discrimination between numerically small shoals (≤4 fish) and also between numerically large (≥4 fish) shoals of conspecifics. We found angelfish not to be able to remember the location of larger versus smaller shoals in the small number range, but to exhibit significant memory for the larger shoal in the large number range as long as the ratio between these shoals was at least 2:1. These results, together with prior findings, suggest the existence of two separate quantity estimation systems, the object file system for small number of items that does not work with the longer retention interval and the analogue magnitude system for larger number of items that does.     

Development and testing of a rapid method for measuring shoal size discrimination

The shoal-choice test is a popular method to investigate quantity discrimination in social fish based on their spontaneous preference for the larger of two shoals. The shoal-choice test usually requires a long observation time (20–30 min), mainly because fish switch between the two shoals with low frequency, thus reducing the possibilities of comparison. This duration limits the use of the shoal-choice test for large-scale screenings. Here, we developed a new version of the shoal-choice test in which the subject was confined in a large transparent cylinder in the middle of the tank throughout the experiment to bound the minimum distance from the stimulus shoals and favour switching. We tested the new method by observing guppies (Poecilia reticulata) in a 4 versus 6 fish discrimination (experiment 1). The new method allowed for a faster assessment of the preference for the larger shoal (<5 min), resulting in potential application for large population screenings. Guppies switched five times more frequently between the two shoals and remained close to the first chosen shoal ten times less compared to experiments with the old method. In experiment 2, we found that with the new method guppies were able to discriminate up to 5 versus 6 fish, a discrimination that was not achieved with the classical method. This last result indicates that minor methodological modifications can lead to very different findings in the same species and suggests that caution should be exercised when interpreting inter-specific differences in quantitative abilities.     

Spontaneous discrimination of small quantities: shoaling preferences in angelfish (<Emphasis Type="Italic">Pterophyllum scalare</Emphasis>)

The ability to quantify, i.e. to estimate quantity, may provide evolutionary advantages in some contexts and has been demonstrated in a variety of animal species. In a prior study, we showed that angelfish (Pterophyllum scalare) were able to discriminate between groups (shoals) in which a large number of conspecifics swam preferring to join the larger of the two. Our results implied that angelfish can compare relative shoal sizes likely on the basis of some quantitative attributes of the shoal. Here, also using a binary preference test, we examined whether angelfish are able to discriminate between shoals of small numbers of conspecifics, and if so whether their performance reveals a comparable underlying mechanism to that proposed for discrimination of small quantities in human and non-human animals, namely the possible precursor of the ability to count. Our results demonstrate that fish reliably chose 4 versus 1, 3 versus 1, 2 versus 1 and 3 versus 2 individuals, but were at chance performance level when having to choose between 4 versus 3, 5 versus 4 and 6 versus 5. Findings also reveal that the density of the fish in the stimulus shoals did not significantly affect the performance of experimental angelfish. These results are compatible with the hypothesis of the existence of an object-file mechanism to discriminate small quantities in vertebrates and provide evidence for spontaneous discrimination of up to three elements in angelfish, a similar limit to that found in human and non-human animals. The findings add to the growing body of data, suggesting that the mechanisms underlying discrimination between different quantities of items may be shared across different taxa and have an evolutionary ancient origin.     

Cleaner fish <Emphasis Type="Italic">Labroides dimidiatus</Emphasis> discriminate numbers but fail a mental number line test

Several species of primates, including humans, possess a spontaneous spatial mental arrangement (i.e. mental number line MNL) of increasing numbers or continuous quantities from left to right. This cognitive process has recently been documented in domestic chicken in a spatial–numerical task, opening the possibility that MNL is a cognitive capacity that has been conserved across vertebrate taxa. In this scenario, fish might possess the MNL as well. Here we investigated whether cleaner fish Labroides dimidiatus show evidence for MNL in two experiments. In Experiment I, we tested fish’s abilities in number discrimination, presenting simultaneously either small (2 vs 5) or large (5 vs 8) continuous quantities where one quantity was systematically rewarded. Experiment II used a protocol of an MNL task similar to the study on chickens. We trained cleaners with a target number (i.e. 5 elements), then we presented them with an identical pair of panels depicting either 2 elements or 8 elements, and we recorded their spontaneous choice for the left or right panel on each presentation. Cleaner fish showed high abilities in discriminating small and large numbers in Experiment I. Importantly, cleaners achieved this discrimination using numerical cues instead of non-numerical cues such as the cumulative surface area, density, and overall space. In contrast, cleaners did not allocate continuous quantities to space in Experiment II. Our findings suggest that cleaner fish possess numbering skills but they do not have an MNL. While similar studies on animals from various clades are needed to trace the evolution of MNL within vertebrates, our results suggest that this cognitive process might not be a capacity conserved across all vertebrate taxa.     

Limitations in advance task preparation: Switching the relevant stimulus dimension in speeded same—different comparisons

When participants switch between relevant stimulus dimensions in speeded classification tasks, taskswitching cost is reduced by advance preparation. Previous studies in which speeded classification tasks were used have suggested that this effect results from attending to the relevant stimulus dimension. Because selective attention to the relevant stimulus dimension in same—different judgments is relatively poor (e.g., Santee &; Egeth, 1980), it was predicted that advance task preparation for a shift in the relevant stimulus dimension would be compromised. This prediction was borne out in two experiments comparing dimension shifts (shape vs.fill) with task rule shifts (same? vs.different?) and shifts in the mapping of right—left keys toyes and_to responses (yes—no vs.no—yes). The results indicate that advance attentional selection of the relevant dimension is an optional preparatory strategy in task switching, employed only in conditions enabling flexible refocusing of attention.     

Sources of Meaning in Life Among Chinese University Students

The current studies were designed to explore the structure of sources of meaning in life among Chinese university students. In Study 1, we content-analyzed 171 students’ answers to the question of what made their lives meaningful and derived 74 frequently mentioned ideas. Then, we composed a questionnaire based on these ideas and administered it to another sample of 523 university students in Study 2. Seven underlying dimensions were identified through exploratory factor analysis: Self-development (i.e., to accomplish one’s aspirations and actualize one’s potential), social commitment (i.e., to contribute to society and to adhere to moral principles), interpersonal relationships (i.e., relationships with family members, friends and others), secular pursuits (i.e., stable jobs, material possessions and social status), experiences in life (i.e., to experience all the joys and sorrows in life), civilization (i.e., reading, thinking, music and arts), and autonomy (i.e., to make decisions freely and take charge of one’s own life). Results are discussed in light of the philosophical influences in Chinese culture, especially those from Confucianism and Taoism.     

Measuring discriminability when there are multiple sources of bias

Performance measures such as log d and d′?aim to measure stimulus discriminability independently of response bias in conditional discrimination tasks, including the yes/no signal-detection procedure. However, they assume only one dimension of bias (e.g., response color) and do not account for bias on additional dimensions (e.g., response side). Such bias reduces log d, thus violating the statistical independence of discriminability and bias measurements. We modified log d to account for side bias and reanalyzed previous side-biased data. With strong side bias, the modified log d differed enough from the standard log d to potentially alter the conclusions of an experiment. Simulations showed that the modified log d produces discriminability estimates that are more accurate and bias-independent than the standard log d calculation.     

Distinct neuronal patterns of positive and negative moral processing in psychopathy

Psychopathy is a disorder characterized by severe and frequent moral violations in multiple domains of life. Numerous studies have shown psychopathy-related limbic brain abnormalities during moral processing; however, these studies only examined negatively valenced moral stimuli. Here, we aimed to replicate prior psychopathy research on negative moral judgments and to extend this work by examining psychopathy-related abnormalities in the processing of controversial moral stimuli and positive moral processing. Incarcerated adult males (N = 245) completed a functional magnetic resonance imaging protocol on a mobile imaging system stationed at the prison. Psychopathy was assessed using the Hare Psychopathy Checklist–Revised (PCL-R). Participants were then shown words describing three types of moral stimuli: wrong (e.g., stealing), not wrong (e.g., charity), and controversial (e.g., euthanasia). Participants rated each stimulus as either wrong or not wrong. PCL-R total scores were correlated with not wrong behavioral responses to wrong moral stimuli, and were inversely related to hemodynamic activity in the anterior cingulate cortex in the contrast of wrong > not wrong. In the controversial > noncontroversial comparison, psychopathy was inversely associated with activity in the temporal parietal junction and dorsolateral prefrontal cortex. These results indicate that psychopathy-related abnormalities are observed during the processing of complex, negative, and positive moral stimuli.     

Recognition during recall failure: Semantic feature matching as a mechanism for recognition of semantic cues when recall fails

Research suggests that a feature-matching process underlies cue familiarity-detection when cued recall with graphemic cues fails. When a test cue (e.g., potchbork) overlaps in graphemic features with multiple unrecalled studied items (e.g., patchwork, pitchfork, pocketbook, pullcork), higher cue familiarity ratings are given during recall failure of all of the targets than when the cue overlaps in graphemic features with only one studied target and that target fails to be recalled (e.g., patchwork). The present study used semantic feature production norms (McRae et al., Behavior Research Methods, Instruments, & Computers, 37, 547–559, 2005) to examine whether the same holds true when the cues are semantic in nature (e.g., jaguar is used to cue cheetah). Indeed, test cues (e.g., cedar) that overlapped in semantic features (e.g., a_tree, has_bark, etc.) with four unretrieved studied items (e.g., birch, oak, pine, willow) received higher cue familiarity ratings during recall failure than test cues that overlapped in semantic features with only two (also unretrieved) studied items (e.g., birch, oak), which in turn received higher familiarity ratings during recall failure than cues that did not overlap in semantic features with any studied items. These findings suggest that the feature-matching theory of recognition during recall failure can accommodate recognition of semantic cues during recall failure, providing a potential mechanism for conceptually-based forms of cue recognition during target retrieval failure. They also provide converging evidence for the existence of the semantic features envisaged in feature-based models of semantic knowledge representation and for those more concretely specified by the production norms of McRae et al. (Behavior Research Methods, Instruments, & Computers, 37, 547–559, 2005).     

Distorted body representations are robust to differences in experimental instructions

Several recent reports have shown that even healthy adults maintain highly distorted representations of the size and shape of their body. These distortions have been shown to be highly consistent across different study designs and dependent measures. However, previous studies have found that visual judgments of size can be modulated by the experimental instructions used, for example, by asking for judgments of the participant’s subjective experience of stimulus size (i.e., apparent instructions) versus judgments of actual stimulus properties (i.e., objective instructions). Previous studies investigating internal body representations have relied exclusively on ‘apparent’ instructions. Here, we investigated whether apparent versus objective instructions modulate findings of distorted body representations underlying position sense (Exp. 1), tactile distance perception (Exp. 2), as well as the conscious body image (Exp. 3). Our results replicate the characteristic distortions previously reported for each of these tasks and further show that these distortions are not affected by instruction type (i.e., apparent vs. objective). These results show that the distortions measured with these paradigms are robust to differences in instructions and do not reflect a dissociation between perception and belief.     

Group Agents and Their Responsibility

Group agents are able to act but are not literally agents. Some group agents, e.g., we-mode groups and corporations, can, however, be regarded as functional group agents that do not have “intrinsic” mental states and phenomenal features comparable to what their individual members on biological and psychological grounds have. But they can have “extrinsic” mental states, states collectively attributed to them—primarily by their members. In this paper, we discuss the responsibility of such group agents. We defend the view that if the group members have accepted the group agent’s (attributed) attitudes and are committed to them, we can favorably compare the situation with the case of individual human agents and a group agent can be regarded as morally responsible for its intentional activities.     

Subtypes of Adaptive and Maladaptive Perfectionism in Anorexia Nervosa: Associations with Eating Disorder and Affective Symptoms

Perfectionism is hypothesized to contribute to the etiology of anorexia nervosa (AN). However, there is little research regarding whether individuals with AN can be classified according to maladaptive (e.g., evaluative concerns) and adaptive (e.g., high personal standards) facets of perfectionism that predict distinct outcomes and might warrant different intervention approaches. In this study, a latent profile analysis was conducted using data from adults with AN (n?=?118). Frost Multidimensional Perfectionism Scale (Frost et al. Cognitive Therapy and Research, 14(5), 449–46, 1990) subscales were used to identify subgroups differing according to endorsed perfectionism features (e.g., adaptive and maladaptive perfectionism). Generalized linear models were used to compare subgroups on eating disorder and affective symptoms measured through questionnaire and ecological momentary assessment. Four subgroups were identified: (a) Low Perfectionism; (b) High Adaptive and Maladaptive Perfectionism; (c) Moderate Maladaptive Perfectionism; and (d) High Maladaptive Perfectionism. Subgroups differed on overall eating disorder symptoms (p?<?.001), purging (p?=?.005), restrictive eating (p?<?.001), and body checking (p?<?.001) frequency, depressive (p?<?.001) and anxiety (p?<?.001) symptoms, and negative (p?=?.001) and positive (p?<?.001) affect. The Low Perfectionism group displayed the most adaptive scores and the Moderate and High Maladaptive Perfectionism groups demonstrated the most elevated clinical symptoms. The High Adaptive and Maladaptive Perfectionism group demonstrated low affective disturbances, but elevated eating disorder symptoms. Results support the clinical significance of subtyping according to perfectionism dimensions in AN. Research is needed to determine if perfectionism subtyping can enhance individualized treatment targeting in AN.     

Do fish count? Spontaneous discrimination of quantity in female mosquitofish

The spontaneous tendency to join the largest social group was used to investigate quantity discrimination in fish. Fish discriminated between shoals that differed by one element when the paired numbers were 1vs2, 2vs3 and 3vs4, but not when 4vs5 or larger. Using large numerosities (>4), the ability to discriminate between two numbers improved as the numerical distance between them increased and a significant discrimination was found only with ratios of 1:2 or smaller (4vs8, 8vs16 and 4vs10). Experiments to control for non-numerical variables evidenced the role played by the total area of stimuli with both large and small numerosities; the total quantity of movement of the fish within a shoal appeared also important but only when large numerosities were involved. Even though the pattern of discrimination exhibited by female mosquitofish is not fully consistent with any of the existing models of quantity representation, our results seem to suggest two distinct mechanisms in fish, one used to compare small numbers of objects and one used when larger numerosities are involved.     

<Emphasis Type="Italic">Above</Emphasis>, <Emphasis Type="Italic">on</Emphasis>, or <Emphasis Type="Italic">shang</Emphasis> (上)? Language and spatial representations among English–Mandarin bilinguals

This study investigated if exposure to spatial language could affect spatial cognition in English-Mandarin bilinguals by focusing on contact/noncontact distinctions, an area that has been a source of contention in the language-and-thought literature. Sixty-three participants were first primed with sentences containing spatial terms (e.g., above, on) before performing a spatial decision task. Approximately half of the participants (n = 33) were primed in English; for the remaining participants (n = 30), primes comprising Mandarin spatial terms―which mark spatial distinctions differently than in English (e.g., shang in Mandarin signifies both above and on in English)―were employed instead. Our findings revealed that participants’ performance was influenced by spatial primes in the English experiment, thereby proffering evidence for thinking-for-speaking effects. However, these findings were not mirrored for the Mandarin experiment, confirming that the contact/noncontact specificity of spatial terms may have been instrumental in engendering the thinking-for-speaking effects observed in English.     

Verbal reaction times to hues vs hue names and forms vs form names

Iwo choice reaction time (RI) studies were carried out in which different classes of stimuli—hues vs hue names in one study and forms vs form names in the other—occurred in independent lists of2, 4, and6 equally probable alternatives. Mean choice RIs were faster for hue names and form names than for hues and forms with4 and6 alternatives, but no significant differences were found in the2-stimulus lists. In both studies, significant list length by stimulus type (e.g., hues vs hue names) interactions indicated greater increase in mean RI with increases in list length for forms and hues than for form names and hue names. It was concluded that differential amounts of generalization of interference aceounted for the interactions. Effects of experimental variables on inferred components of RI were also examined.     

Aging and visual 3-D shape recognition from motion

Two experiments were conducted to evaluate the ability of younger and older adults to recognize 3-D object shape from patterns of optical motion. In Experiment 1, participants were required to identify dotted surfaces that rotated in depth (i.e., surface structure portrayed using the kinetic depth effect). The task difficulty was manipulated by limiting the surface point lifetimes within the stimulus apparent motion sequences. In Experiment 2, the participants identified solid, naturally shaped objects (replicas of bell peppers, Capsicum annuum) that were defined by occlusion boundary contours, patterns of specular highlights, or combined optical patterns containing both boundary contours and specular highlights. Significant and adverse effects of increased age were found in both experiments. Despite the fact that previous research has found that increases in age do not reduce solid shape discrimination, our current results indicated that the same conclusion does not hold for shape identification. We demonstrated that aging results in a reduction in the ability to visually recognize 3-D shape independent of how the 3-D structure is defined (motions of isolated points, deformations of smooth optical fields containing specular highlights, etc.).     

The Multilevel Modality-Switch Effect: What Happens When We See the Bees Buzzing and Hear the Diamonds Glistening

Previous studies demonstrated that the sequential verification of different sensory modality properties for concepts (e.g., BLENDER-loud; BANANA-yellow) brings about a processing cost, known as the modality-switch effect. We report an experiment designed to assess the influence of the mode of presentation (i.e., visual, aural) of stimuli on the modality-switch effect in a property verification and lexical decision priming paradigm. Participants were required to perform a property verification or a lexical decision task on a target sentence (e.g., “a BEE buzzes”, “a DIAMOND glistens”) presented either visually or aurally after having been presented with a prime sentence (e.g., “the LIGHT is flickering”, “the SOUND is echoing”) that could either share both, one or none of the target’s mode of presentation and content modality. Results show that the mode of presentation of stimuli affects the conceptual modality-switch effect. Furthermore, the depth of processing required by the task modulates the complex interplay of perceptual and semantic information. We conclude that the MSE is a task-related, multilevel effect which can occur on two different levels of information processing (i.e., perceptual and semantic).     

Childhood and Adulthood Socioeconomic Statuses in Relation to Union Interest: Exploratory Surface Relationships

Using response surface methodology for exploratory data, we examined the linear and nonlinear surface relationships between no mobility and mobility in reference to union interest defined by willingness to join a labor union. Analyses were conducted on survey data collected from U.S. nonunion employees (N?=?1,010) who indicated their socioeconomic status (SES) in childhood and adulthood in reference to social class, education, and English language/literacy (e.g., language/literacy during childhood, language/literacy now). Surface relationships were mostly linear. For example, among status indicators, a linear surface was found for employees whose childhood and adulthood language/literacy were the same (no mobility): Lower status nonmobile employees showed more union interest than higher status nonmobile employees. In contrast, a nonlinear surface was found for employees whose childhood and adulthood language/literacy were not the same (mobility): Upwardly mobile employees showed less union interest than downwardly mobile employees showed more interest. Details of the surface relationships and future modeling of the relationships in terms of mediational processes are discussed.     

Does test-enhanced learning transfer for triple associates?

Test-enhanced learning and transfer for triple-associate word stimuli was assessed in three experiments. In each experiment, training and final-test trials involved the presentation of two words per triple associate (triplet), with the third word having to be retrieved. In agreement with the prior literature on different stimuli, training through testing with feedback yielded markedly better final-test performance than did restudy. However, in contrast to the positive transfer reported for paired associate stimuli, minimal or no positive transfer was observed, relative to a restudy control, from a trained cue combination (e.g., A, B, ?) to other cue combinations from the same triplet that required a different response (e.g., B, C, ?). That result also held when two unique cue combinations per triplet were tested during training, and for triplets with low and high average associative strengths. Supplementary analyses provided insight into the overall transfer effect: An incorrect response during training appears to yield positive transfer relative to restudy, whereas a correct response appears to yield no, or even negative, transfer. Cross-experiment analyses indicated that test-enhanced learning is not diminished when two or three cue combinations are presented during training. Thus, even though learning through testing is highly specific, testing on all possible stimulus–response combinations remains the most efficient strategy for the learning of triple associates.