Oddity learning by African dwarf goats ( Capra hircus)

Seventeen African dwarf goats (adult females) were trained on oddity tasks using an automated learning device. One odd stimulus and three identical nonodd stimuli were presented on a screen divided into four sectors; the sector for the odd stimulus was varied pseudorandomly. Responses to the odd stimulus were deemed to be correct and were reinforced with food. In phase 1, the goats were trained on eight stimulus configurations. From trial to trial the odd discriminandum was either a + symbol or the letter S, and the nonodd discriminandum was the symbol not used as the odd one. In phase 2, the animals were similarly trained using an unfilled triangle or a filled (i.e., solid black) circle. In phase 3, three new discriminanda were used, an unfilled, small circle with radiating lines, an unfilled heart-shaped symbol, and an unfilled oval; which of the three discriminanda was odd and nonodd was varied from trial to trial. Following these training phases, a transfer test was given, which involved 24 new discriminanda sets. These were presented twice for a total of 48 transfer test trials. Results early in training showed approximately 25% correct, which might be expected by chance in a four-choice task. After 500-2,000 trials, results improved to approximately 40-44% correct. The best-performing subject reached 60-80% correct during training. On the transfer test, this subject had 47.9% correct and that significantly exceeded 25% expected by chance. This finding suggests that some exceptional individuals of African dwarf goats are capable of learning the oddity concept.     

The cognitive capabilities of farm animals: categorisation learning in dwarf goats (Capra hircus)

The ability to establish categories enables organisms to classify stimuli, objects and events by assessing perceptual, associative or rational similarities and provides the basis for higher cognitive processing. The cognitive capabilities of farm animals are receiving increasing attention in applied ethology, a development driven primarily by scientifically based efforts to improve animal welfare. The present study investigated the learning of perceptual categories in Nigerian dwarf goats (Capra hircus) by using an automated learning device installed in the animals' pen. Thirteen group-housed goats were trained in a closed-economy approach to discriminate artificial two-dimensional symbols presented in a four-choice design. The symbols belonged to two categories: category I, black symbols with an open centre (rewarded) and category II, the same symbols but filled black (unrewarded). One symbol from category I and three different symbols from category II were used to define a discrimination problem. After the training of eight problems, the animals were presented with a transfer series containing the training problems interspersed with completely new problems made from new symbols belonging to the same categories. The results clearly demonstrate that dwarf goats are able to form categories based on similarities in the visual appearance of artificial symbols and to generalise across new symbols. However, the goats had difficulties in discriminating specific symbols. It is probable that perceptual problems caused these difficulties. Nevertheless, the present study suggests that goats housed under farming conditions have well-developed cognitive abilities, including learning of open-ended categories. This result could prove beneficial by facilitating animals' adaptation to housing environments that favour their cognitive capabilities.     

Learning to learn during visual discrimination in group housed dwarf goats (Capra hircus)

Using an automated learning device, we investigated "learning to learn" by dwarf goats (Capra hircus) in what was for them a familiar environment and normal social settings. Nine problems, each consisting of four discriminable black symbols, each with one S-super+ and three different S-super(-), were presented on a computer screen. Mean daily learning success improved over the course of the first four problems, and the improvement was maintained throughout the remaining five problems. The number of trials to reach the learning criterion decreased significantly beginning with problem four. Such results may be interpreted as evidence that the goats were developing a learning set. In the present case, the learning set appeared to have two components. One involved gaining familiarity and apparent understanding of the learning device and the basic requirements of the discrimination task. The second component involved learning potential error factors to be ignored, as well as learning commonalities that carried over from one problem to the next. Among the error factors, evidence of apparent preferences for specific symbols was seen, which had a predictable effect on performances.     

Self-controlled visual discrimination learning of group-housed dwarf goats (Capra hircus): behavioral strategies and effects of relocation on learning and memory

In most studies on animal learning, individual animals are tested separately in a specific learning environment and with a limited number of trials per day. An alternative approach is to test animals in a familiar environment in their social group. In this study, the authors--applying a fully automated learning device--investigated voluntary, self-controlled visual shape discrimination learning of group-housed dwarf goats (Capra hircus). The majority of the tested goats showed successful shape discrimination, which indicates the adaptive value of an effective learning strategy. However, in each group, a few individual goats developed behavioral strategies different from shape discrimination to get reward. Relocation impairs memory retrieval (probably by attention shifting) only temporarily for previously learnt shapes. The results demonstrate the usefulness of a self-controlled learning paradigm to assess learning abilities of social species in their normal social settings. This may be especially relevant for captive animals to improve their welfare.     

Responses of dairy heifers to the visual cliff formed by a herringbone milking pit: evidence of fear of heights in cows (Bos taurus)

The ability of cows (Bos taurus) to perceive depth has never been experimentally investigated. If cows can perceive depth, the milking pit in commercial milking facilities may be fear provoking for dairy cows, as past research has shown that most land-dwelling species possess an instinctive fear of heights. In the current study, 12 dairy heifers (1-year-old cows) were exposed to a milking pit (depth-exposed group) and 13 heifers (control group) were exposed to a standard change in the environment while they moved through a milking facility over a 5-day treatment period. Heifers in the depth-exposed group showed a higher heart rate (p < .05) and stopped more often (p < .05) than did those in the control group; persistence of heart rate but not of behavioral responses on repeated exposures indicated that some habituation to the depth stimulus had occurred. Depth exposure had no effect on cortisol concentrations or on ease of handling. These results indicate that heifers responded differently to a change in depth than they did to a standard change in the environment and provide evidence of both depth perception and acute fear of heights in cows.     

Hearing in two cricetid rodents: wood rat (Neotoma floridana) and grasshopper mouse (Onychomys leucogaster)

The audiograms of two wood rats and three grasshopper mice were determined with a conditioned avoidance procedure. The wood rats were able to hear tones from 940 Hz to 56 kHz at a level of 60 dB (SPL), with their best sensitivity of -3 dB occurring at 8 kHz. The hearing of the grasshopper mice ranged from 1.85 kHz to 69 kHz at 60 dB (SPL), with their best sensitivity of 9 dB also occurring at 8 kHz. These results support the relation between interaural distance and high-frequency hearing and between high- and low-frequency hearing. The inability of the grasshopper mouse to hear low frequencies as well as other desert rodents such as kangaroo rats and gerbils demonstrates that not all rodents found in deserts have developed good low-frequency hearing. The degree to which general and specific selective pressures have played a role in the evolution of rodent hearing is discussed.     

Hearing and vocalizations in the orange-fronted conure (Aratinga canicularis)

The auditory sensitivities of the orange-fronted conure (Aratinga canicularis) were examined in relation to the spectral characteristics of its vocalizations. Absolute thresholds, masked thresholds, frequency difference limens, and intensity difference limens for pure tones were obtained using psychoacoustic techniques. In general, hearing abilities are similar to those found in many avian auditory generalists. One exception is the unusually low critical ratio (masked threshold) between 2.0 and 4.0 kHz, similar to that previously found in the budgerigar (Melopsittacus undulatus). These auditory sensitivities were compared with average spectra for (a) contact calls and (b) a general sample of vocalizations recorded from wild birds. The spectral regions of both greatest vocal energy and best auditory sensitivity were between 2.0 and 5.0 kHz.     

Perceptual grouping in two visually reliant species: humans (Homo sapiens) and Australian sea lions (Neophoca cinerea).

Kurylo, van Nest, and Knepper (1997 Journal of Comparative Psychology 111 126-134) have recently shown that hooded rats are able to judge the global orientation of an array of elements if orientation is signalled by the perceptual-grouping principle of proximity, but not if it is signalled by element alignment. Using a procedure designed to overcome some potential problems with the experiment of Kurylo et al, we found the same distinction in the perceptual processing of Australian sea lions. The sea lions were able to judge the orientation of arrays containing strong proximity and similarity information, but performed at chance levels judging arrays in which element alignment signalled global orientation. Human subjects were able to judge all three pattern types quickly and accurately. This is strong evidence of a qualitative distinction in the way in which perceptual grouping operates in humans and the non-human species tested. Whether this distinction is a consequence of evolutionary or experiential factors is a question for future research, but the mere fact of a qualitative difference holds important implications for our understanding of perceptual grouping.     

Sound localization in an Old-World fruit bat (Rousettus aegyptiacus): acuity, use of binaural cues, and relationship to vision.

The passive sound-localization acuity of Egyptian fruit bats (Rousettus aegyptiacus) was determined using a conditioned-avoidance procedure. The mean minimum audible angle for left-right discrimination for 3 bats was 11.6 degrees--very near the mean for terrestrial mammals. The bats also were able to localize low- and high-frequency pure tones, indicating that they can use both binaural phase-difference and binaural intensity-difference cues to localize sound. Moreover, they were able to use the binaural phase-difference cue up to at least 5.6 kHz, which is higher than other mammals yet tested. The width of the Egyptian fruit bats' field of best vision was 27 degrees. This value is consistent with the hypothesis that the role of passive sound localization is to direct the eyes for visual scrutiny of sound sources. Thus, the passive localization abilities of these echolocating megachiropteran fruit bats do not deviate from the patterns established for nonecholocating mammals.     

The Personal Disturbance Scale (sAD): normative data and latent structure in a large non-clinical sample

The Personal Disturbance Scale [sAD; Bedford & Foulds (1978) Delusions–Symptoms–States Inventory State of Anxiety and Depression. Windsor: NFER-Nelson] is widely used in diverse settings and yet there are unresolved issues concerning its psychometric properties and normative data for the English speaking version are limited. The sAD was administered to a large sample of the general adult population (N=758). Demographic variables (gender, age, years of education and occupational status) had only very modest influences on sAD scores. Tables are presented for conversion of raw scores on the Anxiety, Depression and Total scales to percentiles. The sAD scales possessed adequate convergent and discriminant validity, as demonstrated by their pattern of correlations with two other measures of depression and anxiety (the DASS and the HADS). Ten competing models of the latent structure of the sAD were derived from theoretical and empirical sources. These models were evaluated using confirmatory factor analysis. The best fitting model (CFI=0.96) had a tripartite structure, and consisted of a general factor of psychological distress/negative affectivity (all items loaded on this factor) plus orthogonal specific factors of anxiety and depression. Correlated errors specified according to previous empirical findings were permitted. The theoretical and practical implications of this latent structure are discussed.     

The Prospective and Retrospective Memory Questionnaire (PRMQ): Normative data and latent structure in a large non-clinical sample

The Prospective and Retrospective Memory Questionnaire (PRMQ; Smith, Della Sala, Logie, & Maylor, 2000) was developed to provide a self-report measure of prospective and retrospective memory slips in everyday life. It consists of sixteen items, eight asking about prospective memory failures, and eight concerning retrospective failures. The PRMQ was administered to a sample of the general adult population (N = 551) ranging in age between 17 and 94. Ten competing models of the latent structure of the PRMQ were derived from theoretical and empirical sources and were tested using confirmatory factor analysis. The model with the best fit had a tripartite structure and consisted of a general memory factor (all items loaded on this factor) plus orthogonal specific factors of prospective and retrospective memory. The reliabilities (internal consistency) of the Total scale and the Prospective and Retrospective scales were acceptable: Cronbach's alpha was 0.89, 0.84, and 0.80, respectively. Age and gender did not influence PRMQ scores, thereby simplifying the presentation and interpretation of normative data. To ease interpretation of scores on the PRMQ, tables are presented for conversion of raw scores on the Total scale and Prospective and Retrospective scales to T scores (confidence limits on scores are also provided). In addition, tables are provided to allow users to assess the reliability and abnormality of differences between an individual's scores on the Prospective and Retrospective scales.     

The Prospective and Retrospective Memory Questionnaire (PRMQ): Normative data and latent structure in a large non-clinical sample

The Prospective and Retrospective Memory Questionnaire (PRMQ; Smith, Della Sala, Logie, & Maylor, 2000) was developed to provide a self-report measure of prospective and retrospective memory slips in everyday life. It consists of sixteen items, eight asking about prospective memory failures, and eight concerning retrospective failures. The PRMQ was administered to a sample of the general adult population (N = 551) ranging in age between 17 and 94. Ten competing models of the latent structure of the PRMQ were derived from theoretical and empirical sources and were tested using confirmatory factor analysis. The model with the best fit had a tripartite structure and consisted of a general memory factor (all items loaded on this factor) plus orthogonal specific factors of prospective and retrospective memory. The reliabilities (internal consistency) of the Total scale and the Prospective and Retrospective scales were acceptable: Cronbach's alpha was 0.89, 0.84, and 0.80, respectively. Age and gender did not influence PRMQ scores, thereby simplifying the presentation and interpretation of normative data. To ease interpretation of scores on the PRMQ, tables are presented for conversion of raw scores on the Total scale and Prospective and Retrospective scales to T scores (confidence limits on scores are also provided). In addition, tables are provided to allow users to assess the reliability and abnormality of differences between an individual's scores on the Prospective and Retrospective scales.     

Discriminating the relation between relations: the role of entropy in abstract conceptualization by baboons (Papio papio) and humans (Homo sapiens).

Two baboons (Papio papio) successfully learned relational matching-to-sample: They picked the choice display that involved the same relation among 16 pictures (same or different) as the sample display, although the sample display shared no pictures with the choice displays. The baboons generalized relational matching behavior to sample displays created from novel pictures. Further experiments varying the number of sample pictures and the mixture of same and different sample pictures suggested that entropy plays a key role in the baboons' conceptual behavior. Two humans (Homo sapiens) were similarly trained and tested; their behavior was both similar to and different from the baboons' behavior. The results suggest that animals other than humans and chimpanzees can discriminate the relation between relations. They further suggest that entropy detection may underlie same-different conceptualization, but that additional processes may participate in human conceptualization.     

Spontaneous classification in action by a human-enculturated and language-reared bonobo (Pan paniscus) and common chimpanzees (Pan troglodytes).

The authors investigated the formal features of spontaneous manipulations used by 1 bonobo (Pan paniscus) and 2 common chimpanzees (Pan troglodytes) to classify objects in action. Chimpanzees' manipulations were evenly split between serial, one-at-a-time acts on 1 object and parallel, two-at-a-time acts on 2 or 3 objects. Chimpanzees systematically combined their manipulations into routines to generate class-consistent categories of objects. Their routines featured much reproduction of the same manipulations, planful acts that anticipated follow-up manipulations, and manipulations that were reciprocal to each other to accomplish an end. In all these respects, chimpanzees' manipulations were similar to those of 2-year-old human infants. In others they differed. Chimpanzees' routines were mainly based on a linear integration of manipulations. Classifying in action was only infrequently produced by hierarchically integrated routines.     

Fear survey schedule (II): Normative data and factor analyses based upon a large college sample

A fear survey schedule (FSS-II) was administered to 1814 undergraduates at the University of Illinois. Females reported significantly more fear than males. Factor analyses indicated that FSS-II taps the following major fear areas: Live Organisms, Death and Illness, Social Interaction, and Social Evaluation. Problems associated with the use of FSS-II total scores for subject selection purposes and with the unsupplemented use of verbal report fear measures were discussed.     

Periventricular leukomalacia (PVL): an identical twin case study illustration of white matter dysfunction and nonverbal learning disability (NLD).

This paper discusses the implications of Periventricular Leukomalacia (PVL) lesions for the development of Nonverbal Learning Disabilities (NLD) as illustrated through an identical twin case study. PVL lesions were identified in an 8-year-old child, but were not detected in his identical twin brother who served as a matched comparison. While the nonclinical twin displayed a largely unremarkable neuropsychological profile, the clinical twin evidenced a distinct pattern of social, intellectual, academic, and neuropsychological test results often identified among children with PVL and those with the NLD syndrome. The clinical and theoretical implications for this case study are discussed.