There are currently more than 25,000 older people with dementia (PwD) from ethnic minority backgr... more There are currently more than 25,000 older people with dementia (PwD) from ethnic minority backgrounds in the UK. This number is expected to increase by 7-fold by 2060. The number of younger PwD remains unknown, but over-diagnosed people younger than 60 in some ethnic minority subgroups have been recorded [1]. Furthermore, since racial and ethnic minorities are expected to become the majority of the population by 2050 in developed countries (i.e., USA), the contingent of PwD from ethnic minorities will dramatically increase. People from ethnic minority backgrounds are more likely to report poor health and have a higher morbidity rate of cardiovascular diseases and diabetes. Thus, their lower dementia incidence rate (6.4%) compared to 9.45% in the white UK population [2] is difficult to explain. Furthermore, there is a disparity in dementia incidence rates among distinct ethnic subgroups. Individuals from Asian ethnic groups have the lowest proportion of dementia diagnoses, followed by individuals from Black ethnic groups. In contrast, individuals from the White ethnic group have the highest proportion of dementia diagnoses [3]. In addition, functional cognitive impairment can be easily misdiagnosed as an enduring neurodegenerative disorder, especially among ethnic minorities [4]. The clinical diagnosis of dementia is not based on a single definitive diagnostic test but entails a comprehensive clinical assessment backed with neurocognitive, neuroradiological, and biochemical assessments [5]. The recommended cognitive tests consist of items that are commonly used to detect principal intellectual deficits associated with dementia, i.e., memory for learned information, ability to learn new information, and tests of attention or concentration. Longer cognitive tests include additional items, e.g., language, verbal fluency, and visuospatial skills. Many ethnic minority people already have two potential sources of under-performance on these commonly used Western cognitive tests: (1) lower educational attainment resulting from their childhood setting and (2) a lack of familiarity with the language and culture of the country they now live in. This may be due to their cultural differences in help-seeking behaviour, language barriers, inadequate cognitive tests, and problems in navigating the healthcare system [1, 6]. It is, thus, not surprising that their dementia remains underdiagnosed [3]. The core clinical criteria for dementia are based on validated neuropsychological tests to assess various cognitive functions, i.e., episodic memory, executive function, language, visual and spatial skills, and attention, preferably accompanied by interviews with the PwD and an informant. A number of these cognitive tests have been translated and adapted for use in low-and middle-income countries, which account for the majority of the UK's immigrant population (i.e., South Asian ethnic groups). However, these tests have not been universally successful in improving dementia diagnostic accuracy among older ethnic minority people. Furthermore, there is a disparity in cognitive tool accuracy among different ethnic subgroups. These include different cutoff points on the Mini-Mental State Exam (MMSE) and great variability in performance, ranging from incomplete clinical evaluation due to a large number of missing values (i.e., 41% in Asian and 39% in Black groups) [3] to relatively good compliance in the small sample-sized studies. Similar findings are reported for the Addenbrooke's Cognitive Examination-III (ACE-III) translations, predominantly conducted on very small sample sizes, with a substantially lower cutoff point for dementia [7]. Different cognitive functions appear to be affected differently in distinct ethnic subgroups. Thus, using the Montreal Cognitive Assessment (MoCA) test, visuospatial/executive, attention, language, delayed recall, and orientation subtests are predictive of clinical dementia diagnosis among non-Hispanic Blacks. Visuospatial/executive, delayed recall, and orientation subtests, as well as education, are predictive among Hispanics, whereas all subtests, education, and age are predictive of dementia diagnosis clinical diagnosis among non-Hispanic Whites [8]. This suggests that cognitive test item discrimination and difficulty may vary with ethnicity and cognitive status. Most memory assessment services in the UK (70%) use alternative standard and validated
Understanding Primate Behaviour: A Cooperative Effort of Field and Laboratory Research
Springer eBooks, 1995
ABSTRACT A separation between field and laboratory research represents a detriment to the discipl... more ABSTRACT A separation between field and laboratory research represents a detriment to the discipline because depending upon the nature of the hypotheses, a given problem may be most appropriately evaluated in the field, in a semi-natural enclosure, in a captive environment, or in a combination of these settings. For this reason it is necessary “to identify means of bridging an apparent chasm that separates some primatologists working in the field from some whose research is carried out primarily in laboratory settings” [29, see also 16].
Humans show a global advantage when processing hierarchical visual patterns, and they detect the ... more Humans show a global advantage when processing hierarchical visual patterns, and they detect the global level of stimulus structure more accurately and faster than the local level in several stimulus contexts. By contrast, capuchins (Cebus apella) and other monkey species show a strong local advantage. A key factor which, if manipulated, could cause an inversion of this effect in monkeys is still to be found. In this study, we examined whether it was possible to induce attention allocation to global and local levels of perceptual analysis in capuchin monkeys and if by doing so, their local dominance could be reversed. We manipulated attentional bias using a matching-to-sample (MTS) task where the proportion of trials requiring global and local processing varied between conditions. The monkeys were compared with humans tested with the same paradigm. Monkeys showed a local advantage in the local bias condition but a global advantage in the global bias condition. The role of attention in processing was confined to the local trials in a first phase of testing but extended to both local and global trials in the course of task practice. Humans exhibited an overall global dominance and an effect of attentional bias on the speed of processing of the global and local level of the stimuli. These results indicate a role for attention in the processing of hierarchical stimuli in monkeys and are discussed in relation to the extent to which they can explain the differences between capuchin monkeys and humans observed in this and other studies.
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit:
Quarterly Journal of Experimental Psychology, Oct 21, 2021
Search-the problem of exploring a space of alternatives in order to identify target goals-is a fu... more Search-the problem of exploring a space of alternatives in order to identify target goals-is a fundamental behaviour for many species. Although its foundation lies in foraging, most studies of human search behaviour have been directed towards understanding the attentional mechanisms that underlie the efficient visual exploration of two-dimensional scenes. With this review, we aim to characterise how search behaviour can be explained across a wide range of contexts, environments, spatial scales, and populations, both typical and atypical. We first consider the generality of search processes across psychological domains. We then review studies of interspecies differences in search. Finally, we explore in detail the individual and contextual variables that affect visual search and related behaviours in established experimental psychology paradigms. Despite the heterogeneity of the findings discussed, we identify that variations in control processes, along with the ability to regulate behaviour as a function of the structure of search space and the sampling processes adopted, to be central to explanations of variations in search behaviour. We propose a tentative theoretical model aimed at integrating these notions and close by exploring questions that remain unaddressed.
The evolutionary perspective: the struggle to define a new scientific domain, introspection and s... more The evolutionary perspective: the struggle to define a new scientific domain, introspection and some methodological insights 1 1.2 Puzzle boxes and Skinner boxes: rat, pigeon, monkey, which is which? It doesn't matter 9 1.3 WGTA: Learning Sets and the study of complex learning skills 1.4 Ape language projects: keyboards, plastic chips and the primacy of the name 19 1.5 Conclusions 23 CHAPTER H: Serially Motivated Behaviour 27 2.1 From Lashley to recent trends in the study of serially organized behaviour 27 2.2 Serial learning: how arbitrarious sequences of responses are learnt 30 2.3 Non-arbitrary series and the role of cognitive regulation 2.4 Conclusions 2.5 The economy/data reduction hypothesis and the development of the experimental program presented in this thesis CHAPTER HI: The familiarisation of the monkeys 60 3.1 A WGTA based search task 60 3.2 Experiment 1 3.3 Experiment 2 3.4 General discussion CHAPTER IV: Touch Screen Based Search Tasks VI 4.1 Introduction 91 4.2 Experiment 1 96 4.3 Experiment 2 4.4 Conclusions CHAPTER V: An Experiment on Spontaneous Classification 164 5.1 Introduction 5.2 Material and Methods 5.3 Data analysis and results 5.4 Conclusions
International Journal of Comparative Psychology, 1997
Nine young children and five tufted capuchin monkeys {Cebus apella) were tested on tasks involvin... more Nine young children and five tufted capuchin monkeys {Cebus apella) were tested on tasks involving a search for an object hidden within a set of plastic cups. As viewed, the sequences of displacements enabled subjects to eliminate some of the possible locations where the object lay hidden, thereby constraining the search space. Both species deployed principled modes of search, in contrast to a random selection strategy. However, no subject from either group proved able to fully constrain the search on the basis of all of the information conveyed over the full menu of tasks. The reasons for incomplete success are as yet unclear, however failures may be due as much to social limitations as to other forms of error. On that basis we conclude that new paradigms are necessary, designed specifically to evaluate competencies for socially based knowledge on the one hand and self-directed search on the other. Memory and representation have a long history of exploration in research on both human and non-human species. Perhaps the oldest form is the delayed-response task pioneered by Hunter (1913), elaborated later with primates by Yerkes (1929), and culminating in the well-known versions introduced by Piaget (1955) as "object permanence" tasks. A common feature of these tests is the role they give the tester who first acts to capture the subject's attention by presenting an attractive object, such as a toy, or a piece of preferred food, before hiding it within containers or behind occluding screens which remain at all times within the test field. Either immediately afterwards, or following a delay, the subject is given an opportunity to seek hidden items. Persistence of search in the absence of direct perceptual information is the first indication of object memory or event permanence. However, beyond search oriented behaviour per se, the use of strategies may indicate a great deal about the subject's ability to
Two experiments using an immersive virtual reality foraging environment determined the spatial st... more Two experiments using an immersive virtual reality foraging environment determined the spatial strategies spontaneously deployed by people in a foraging task and the effects on immediate serial recall of trajectories though the foraging space, which could conform or violate specific organisational constraints. People benefitted from the use of organised search patterns when attempting to monitor their travel though either a clustered ''patchy'' space or a matrix of locations. The results are discussed within a comparative framework.
Immediate serial spatial recall measures the ability to retain sequences of locations in short-te... more Immediate serial spatial recall measures the ability to retain sequences of locations in short-term memory and is considered the spatial equivalent of digit span. It is tested by requiring participants to reproduce sequences of movements performed by an experimenter or displayed on a monitor. Different organizational factors dramatically affect serial spatial recall but they are often confounded or underspecified. Untangling them is crucial for the characterization of working-memory models and for establishing the contribution of structure and memory capacity to spatial span. We report five experiments assessing the relative role and independence of factors that have been reported in the literature. Experiment 1 disentangled the effects of spatial clustering and path-length by manipulating the distance of items displayed on a touchscreen monitor. Long-path sequences segregated by spatial clusters were compared with short-path sequences not segregated by clusters. Recall was more accurate for sequences segregated by clusters independently from path-length. Experiment 2 featured conditions where temporal pauses were introduced between or within cluster boundaries during the presentation of sequences with the same paths. Thus, the temporal structure of the sequences was either consistent or inconsistent with a hierarchical representation based on segmentation by spatial clusters but the effect of structure could not be confounded with effects of path-characteristics. Pauses at cluster boundaries yielded more accurate recall, as predicted by a hierarchical model. In Experiment 3, the systematic manipulation of sequence structure, path-length, and presence of path-crossings of sequences showed that structure explained most of the variance, followed by the presence/absence of path-crossings, and path-length. Experiments 4 and 5 replicated the results of the previous experiments in immersive virtual reality navigation tasks where the viewpoint of the observer changed dynamically during encoding and recall. This suggested that the effects of structure in spatial span are not dependent on perceptual grouping processes induced by the aerial view of the stimulus array typically afforded by spatial recall tasks. These results demonstrate the independence of coding strategies based on structure from effects of path characteristics and perceptual grouping in immediate serial spatial recall.
Previous studies suggest that monkeys process local elements of hierarchical visual patterns more... more Previous studies suggest that monkeys process local elements of hierarchical visual patterns more quickly and more accurately than they process the global shape. These results could be indicative of differences between relatively high visual functions of humans and non-human primates. It is, however, important to rule out that relatively low-level factors can explain these differences. We addressed this issue with two experiments carried out on capuchin monkeys (Cebus apella) using matching-to-sample tasks featuring hierarchical stimuli. The first experiment assessed whether manipulations of stimulus size can affect the local advantage so far observed in this New World monkey species. An overall local versus global advantage still emerges in capuchins, irrespectively of the amplitude of the visual angle subtended by the hierarchical shapes. Moreover, a local-to-global interference, indicative of a strong local advantage, was observed for the first time. In the second experiment, we manipulated size and numerosity of the local elements of hierarchical patterns, mimicking procedures that in human perception relegate the local elements to texture and enhance a global advantage. Our results show that in capuchin monkeys, a local advantage emerges clearly even when these procedures are used. These results are of interest since extensive neurophysiological research is carried out on non-human primate vision, often taking for granted a similarity of visual skills in human and non-human primates. These behavioural results show that this assumption is not always warranted and that more research is needed to clarify the differences in the processes involved in basic visual skills among primates.
Search and serial recall tasks were used in the present study to characterize the factors affecti... more Search and serial recall tasks were used in the present study to characterize the factors affecting the ability of humans to keep track of a set of spatial locations while traveling in an immersive virtual reality foraging environment. The first experiment required the exhaustive exploration of a set of locations following a procedure previously used with other primate and non-primate species to assess their sensitivity to the geometric arrangement of foraging sites. The second experiment assessed the dependency of search performance on search organization by requiring the participants to recall specific trajectories throughout the foraging space. In the third experiment, the distance between the foraging sites was manipulated in order to contrast the effects of organization and traveling distance on recall accuracy. The results show that humans benefit from the use of organized search patterns when attempting to monitor their travel though either a clustered "patchy" space or a matrix of locations. Their ability to recall a series of locations is dependent on whether the order in which they are explored conformed or did not conform to specific organization principles. Moreover, the relationship between search efficiency and search organization is not confounded by effects of traveling distance. These results indicate that in humans, organizational factors may play a large role in their ability to forage efficiently. The extent to which such dependency may pertain to other primates and could be accounted for by visual organization processes is discussed on the basis of previous studies focused on perceptual grouping, search, and serial recall in non-human species.
European Journal of Cognitive Psychology, Mar 1, 2010
and-conditions-of-access.pdf This article may be used for research, teaching and private study pu... more and-conditions-of-access.pdf This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, redistribution , reselling , loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.
The transfer index (TI) is a discrimination reversal paradigm that requires the achievement of a ... more The transfer index (TI) is a discrimination reversal paradigm that requires the achievement of a given prereversal criterion of accuracy. The mediational learning (ML) paradigm is a modification of the T1 procedure that features the presentation of three different reversal conditions designed to assess whether prereversal learning is based on purely associative processes or mediated by the use of a strategy (win-stay~lose-shift). These two paradigms have been used with apes and several Old World monkey species, proving to be effective tools for the comparison of species on the basis of their transfer abtTities and the nature of their learning processes. However, among New World monkeys, only the squirrel monkey has been tested. Capuchin (Cebus spp.) adaptability and their mastery in using tools have led to controversial interpretations of their cognitive and learning skills. We evaluated their mode of learning and the transfer of learning using the TI and the ML paradigms. We tested four tufted capuchins (Cebus apella) in a WGTA ushTg a variety of stbnulus object pairs. The results show that they possess rather good transfer abilities and one subject showed an associative learning mode. None of the subjects showed evidence of learning mediated by a win-stay~lose-shift strategy.
Structure was imposed on a tapping task by requiring participants to reproduce sequences of respo... more Structure was imposed on a tapping task by requiring participants to reproduce sequences of responses to icons organised in spatial clusters. A first experiment featured sequences either segregated or not segregated by clusters. Accuracy was higher for sequences segregated by clusters. Moreover, inter-response times were longer at cluster boundaries than within cluster boundaries. To rule out possible confounding effects of movement length, this temporal pattern was replicated in a second experiment requiring a single response indicating the next sequential step, following the presentation of a portion of a previously practised sequence. These results suggest that sequence reproduction can be sustained by a hierarchical representation based on spatial proximity and provide a first indication of the role of spatial structure in serial-spatial memory.
Review article The serial organisation of behaviour by non-human primates; an evaluation of experimental paradigms
ABSTRACT On close examination of research programs which focus, either implicitly or explicitly, ... more ABSTRACT On close examination of research programs which focus, either implicitly or explicitly, on the problem of the organisation of serial order in non-human primates, it is possible to detect some limitations in the paradigms conventionally used. Serial learning studies, which focus on the acquisition of arbitrary lists of unconnected elements point towards a distinction between the representation of ordered series formed by monkeys and pigeons. However, the use of unconnected items prevents an assay of the degree to which primates might be able to impose a structure over the list to be reported. The study of transitive reasoning has been implemented by means of a paradigm where the order of a series is conveyed by presenting a common item in pairs of binary discriminations. Animals tested with this paradigm develop control strategies using more information than that provided by reward contingencies alone. A restriction of this paradigm is that, in its binary form, it does not allow a differentiation between the performance of monkeys and pigeons and even simple models account for a transitive bias in the task. On the basis of these observations it is proposed that novel paradigms which go beyond the binary context, feature multiple connected items, and accord a high degree of spontaneity to the subjects might allow better than traditional ones to uncover qualitative different ways in which different organisms serially organise their behaviour. Some recent research programs based on such rationale, and implemented as search tasks, are then outlined and compared with other approaches to the study of search behaviour. Preliminary results obtained from these studies indicate that the spontaneous serial organisation of multiple connected items might uncover new dimensions of promising comparative relevance.
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Papers by Carlo De Lillo