Size Of Food Items Research Articles

Dietary Assessment with Multimodal ChatGPT: A Systematic Analysis.

Conventional approaches to dietary assessment are primarily grounded in self-reporting methods or structured interviews conducted under the supervision of dietitians. These methods, however, are often subjective, potentially inaccurate, and time-intensive. Although artificial intelligence (AI)-based solutions have been devised to automate the dietary assessment process, prior AI methodologies tackle dietary assessment in a fragmented landscape (e.g., merely recognizing food types or estimating portion size), and encounter challenges in their ability to generalize across a diverse range of food categories, dietary behaviors, and cultural contexts. Recently, the emergence of multimodal foundation models, such as GPT-4V, has exhibited transformative potential across a wide range of tasks (e.g., scene understanding and image captioning) in various research domains. These models have demonstrated remarkable generalist intelligence and accuracy, owing to their large-scale pre-training on broad datasets and substantially scaled model size. In this study, we explore the application of GPT-4V powering multimodal ChatGPT for dietary assessment, along with prompt engineering and passive monitoring techniques. We evaluated the proposed pipeline using a self-collected, semi free-living dietary intake dataset comprising 16 real-life eating episodes, captured through wearable cameras. Our findings reveal that GPT-4V excels in food detection under challenging conditions without any fine-tuning or adaptation using food-specific datasets. By guiding the model with specific language prompts (e.g., African cuisine), it shifts from recognizing common staples like rice and bread to accurately identifying regional dishes like banku and ugali. Another GPT-4V's standout feature is its contextual awareness. GPT-4V can leverage surrounding objects as scale references to deduce the portion sizes of food items, further facilitating the process of dietary assessment.

Seasonal organization of tintinnid community by temperature preference and LOD size-class in a subtropical brackish embayment

Abstract Most annual studies of tintinnid and phytoplankton in coastal habitats are influenced by alien species introduced by water masses exchange, and therefore cannot be used as direct evidence for exploring the mechanism of annual succession in indigenous community. For brackish communities, very limited annual studies exist because of the difficulty of conducting stable sampling in the transition between freshwater and seawater. The special topography of Xiangshan Bay isolates the external water mass and provides a suitable habitat for exploring the annual succession mechanism of the brackish tintinnid community. In this study, samples were collected from seven stations in Tie Harbor, Xiangshan Bay (East China Sea) during 10 months from 2022 to 2023. A total of 23 tintinnid species of five genera were identified throughout the year. These tintinnid species can be clustered into four seasonal groups, winter, summer, autumn and spring-autumn, with three temperature preferences. The Lorica Oral Diameter (LOD) size-class of each tintinnid species, which determines the food item size of tintinnid, separated their different ecological niches within each seasonal group. The seasonal succession of tintinnid community in Xiangshan Bay was organized by both temperature preference and LOD size of the tintinnid species.

Association between maternal zinc intake and preterm birth in Gansu Province in 2010-2012

To analyze the association between maternal dietary zinc levels at different stages and preterm birth. The subjects were from the 2010-2012 birth cohort of Maternal and Child Health Hospital of Gansu Province, and a total of 10 179 pregnant women were included in the final study. Dietary information before and during pregnancy was collected through semi-quantitative food frequency questionnaire, and daily zinc intake in each period was estimated according to the frequency of consumption and portion size of food items using the Chinese Standard Tables of Food Consumption. Logistic regression was used to analyze the OR value of preterm birth under different maternal dietary zinc levels. The detection rate of preterm birth was 10.0%, of which 81.8% were moderate preterm, 18.3% were very preterm, 33.2% were medically indicated preterm and 66.8% were spontaneous preterm birth. After adjusting for general conditions such as maternal age, education level, and history of preterm birth, compared with the group with the highest zinc intake before and during pregnancy, those with low zinc intake before or during pregnancy had a significantly higher risk of moderate, very, and spontaneous preterm birth. After further controlled of folic acid and fiber intake during pregnancy, compared with the group with the highest zinc intake before and during pregnancy, the risk of very preterm birth(OR=2.04, 95%CI 1.07-3.90) and spontaneous preterm birth(OR=1.38, 95%CI 1.01-1.88) was significantly increased in those with the lowest zinc intake during the third trimester. For pregnant women aged≥30 years(OR=1.55, 95%CI 1.12-2.13) and normal or less normal weight gain during pregnancy(OR=1.51, 95%CI 1.15-1.97), insufficient zinc intake was significantly associated with preterm birth. Maternal low dietary zinc intake during the third trimester was associated with very premature and spontaneous preterm birth.

Diet and Feeding Ecology of the Invasive <i>Gambusia holbrooki</i> (Teleostei: Poeciliidae) in Lotic and Lentic Habitats (Northwestern Part of Turkey)

Received October 13, 2021; revised April 22, 2022; accepted August 15, 2022Abstract—In order to understand the success of the invasion of a non-native fish, it is important to determine its fundamental competition characteristics such as its tolerance to habitat differences and feeding plasticity. This study aimed to determine the invasive characteristics of Gambusia holbrooki Girard, 1859 by investigating the diet and feeding ecology of this non-native fish inhabited in lotic and lentic habitats. A total of 164 G. halbrooki specimens (SL 1.4–4.3 cm) were investigated from the lotic habitats, while 101 (SL 1.6–3.3 cm) ones were from the lentic habitats. The food spectrum of the fish in lotic habitats was composed of 11 food items predominantly of the Diptera (80.9, MI%) and Plant (11.8, MI%). In lentic habitats, the species consumed 10 different food types, and Diptera (96.0, MI%) was followed by the low values of zooplankton groups (Cladocera; 2.2, MI% and Copepoda; 0.8, MI%). The fish that inhabited both lotic and lentic habitats have shown a generalist feeding strategy; while the importance of each food item in the diet indicated the generalization, Diptera presented with high values was the evidence of a relatively narrow niche of the fish in both habitats. An ontogenetic shift was observed in the diet of G. holbrooki and while the diet of juveniles was more limited, the diversity and sizes of food items consumed have increased in parallel with the increase in the size of the fish. With these results, it was thought that G. holbrooki could show a food competition with native fish species in the region by feeding mainly on Diptera, which is also an important food source for most of the native fishes and their young individuals.

Differentials in dietary intake of macro and micronutrients in patients with type 2 diabetes and foot ulcers: Observations from a pilot study.

The dietary profiles of patients with type 2 diabetes mellitus (T2DM) from Southern India have been infrequently studied. We aimed to study the differences in dietary intake of macro and micronutrients in elderly patients of Type 2 diabetes mellitus (T2DM), with and without foot ulcers. Elderly patients with T2DM and foot ulcers (n=79; mean age: 60.6 years) and those without foot ulcers (n=59; mean age: 55.0 years) were studied. Biochemical evaluation for measures of glycemia, lipids and albumin were done and staging of foot ulcers was done using Wagner's scale. A 24-hour dietary recall was administered to quantify the mean daily intake (MDI) of macro, micronutrients and trace elements from portion sizes of food items consumed and compared to the recommended dietary allowance (RDA) for Indians aged 55 years and above. In patients with T2DM and foot ulcers, the MDI of carbohydrates, fats and phosphorus were significantly higher whereas the MDI of proteins and micronutrients namely zinc, folic acid, iron and carotene were lower than the RDA. Elderly patients with nephropathy and longer duration of T2DM have higher odds of developing foot ulcers, when compared to patients without foot ulcers. Elderly patients with T2DM and foot ulcers were deficient in dietary intake of proteins and micronutrients inclusive of carotene, folic acid, zinc, and Iron. Clinical care, regular monitoring of dietary intake and appropriate correction of nutritional deficiencies will aid in the management of diabetic foot ulcers.

Dietary Composition and Its Association with Newly Diagnosed Nonalcoholic Fatty Liver Disease and Insulin Resistance.

Dietary modification is essential for treating nonalcoholic fatty liver disease (NAFLD); however, the dietary components are less well defined. We enrolled 252 adults with no history of liver disease and excessive alcohol use to evaluate the relationship between macronutrients and NAFLD and insulin resistance. Participants took photographs of their meals and documented their food intake in a food diary for seven consecutive days. A dietitian estimated the type and portion size of food items and analyzed nutrients with INMUCAL-Nutrients software. Later, participants underwent transient elastography to diagnose NAFLD and blood tests to measure insulin resistance using the homeostasis model. Total energy intake and the proportion of carbohydrate, fat, and protein consumption did not differ between participants with NAFLD (n = 41) and those without NAFLD (n = 211). Using multiple logistic regression analysis, daily intake of protein < 1.0 g/kg (OR: 3.66, 95% CI: 1.41–9.52) and full-fat dairy product ≥ 50 g (OR: 0.42, 95% CI: 0.18–0.99) were associated with NAFLD. Insulin resistance was associated with a daily intake of protein < 1.0 g/kg (OR: 3.09, 95% CI: 1.59–6.05), full-fat dairy product ≥ 50 g (OR: 0.46, 95% CI: 0.25–0.82), and dietary fiber ≥ 8 g (OR: 0.41, 95% CI: 0.22–0.74). Our data show that a low protein intake increases the odds for NAFLD and insulin resistance. Contrarily, a high intake of full-fat dairy products and dietary fiber has been associated with a potential protective effect against NAFLD and insulin resistance.

Strategies to Reduce Consumption of Unhealthy Foods and Beverages: Scenario Modeling to Estimate the Impact on the Australian Population’s Energy and Nutrient Intakes

BackgroundOverconsumption of energy-dense, nutrient-poor “discretionary” foods and beverages can indicate poor diet quality, which is a risk factor for obesity and chronic disease. With 60% of Australians exceeding the recommended intake of discretionary foods, there is a need for interventions to reduce their consumption. ObjectiveThe objective was to model the impact of 26 specific scenarios to limit discretionary food intake on energy and nutrient intake. DesignThe scenario modeling analysis was based on reduction strategies targeting portion size, frequency, or variety of discretionary food and beverage items consumed. Participants/SettingData from 12,153 respondents aged 2 to 85 years from the 2011-12 Australian National Nutrition and Physical Activity Survey were used. Outcome measuresThe outcome measures were change in servings of discretionary foods and key nutrients (energy, total fat, saturated fat, sugar, alcohol, sodium, trans fat) for the population, and by sex, age group, weight status, and socioeconomic status. Statistical analyses performedDescriptive and inferential statistical analysis were conducted. ResultsScenarios reduced total energy intake by up to 26% across the population as a whole. The removal of discretionary foods (not beverages) resulted in the greatest reduction in servings and energy (74.8% and 25.6%, respectively), followed by the removal of discretionary items in portions greater than 143 kcal (59.1% and 24.3%) and not consuming discretionary items at main meals (51.2% and 17.8%). Targeting single categories of discretionary foods reduced energy intake by an average of 5.6% for the removal of cakes and biscuits, 4.4% for alcohol, and 3.9% for sugar-sweetened beverages. Strategies reduced total fat, saturated fat, and sugar by up to 35%, 38%, and 40% respectively. ConclusionsStrategies that are specific to discretionary food and beverage intake targeting reductions in portion size, frequency, or variety have the potential to reduce energy intake and improve diet quality. These findings have implications for designing interventions with potential to tailor messages to current dietary habits. Exploration of how these strategies could be effectively implemented will be the focus of further research.

Development of the Thai semiquantitative food frequency questionnaire (semi-FFQ) for people at risk for metabolic syndrome

This study aimed to describe the development of a Thai semiquantitative food frequency questionnaire (Thai semi-FFQ) for people at risk people for metabolic syndrome. Data from the Thailand National Food Consumption Survey was used to analyze food lists and portion sizes of single food items. Data for Thai mixed dishes were lacking. Hence, data on mixed dishes were collected from five cafeterias at Siriraj Hospital in Thailand. Three samples of each food item were used to weigh the major ingredients. The nutritive values were calculated using Thai food composition software. Nutrient profiling criteria (NP) were used to classify the selected food items. Ninety-one food items of eight food groups and five serving sizes were included in the Thai semi-FFQ. The food groups were fruits (n = 18), beverages (n = 10), snacks and desserts (n = 29), a la carte (n = 7), noodles (n = 11), rice with toppings (n = 8), eggs (n = 3), and salads (n = 5). The Thai mixed dishes were classified into three groups: a la carte, noodles, and rice with toppings. All mixed dishes were scored by NP criteria, with 13% receiving a ‘grade A’ (score > 16). Thirty four percent were classified as ‘grade B’ (score 12–16), and 53% were given a ‘grade C’ (score < 12). The content validity of mixed dish-based Thai semi-FFQ was evaluated by three nutrition specialists, with a score of 0.97. Our Thai semi-FFQ included single food items and, unlike other Thai FFQs, Thai mixed dish items. This Thai semi-FFQ was useful in assessing dietary food patterns of Thai populations who are at risk for non-communicable diseases.

Food portion size educational programme in a workplace setting in Puducherry - Is it effective?

Background:Consuming larger portion sizes, i.e., in excess of a typically recommended serving size, has been attributed to the obesity epidemic. The workplace acts as an efficient target for health promotion activities.Aims:To assess the effectiveness of a food portion size educational programme in increasing knowledge among the employees of a software company in Puducherry.Methodology:An interventional study was conducted with a pre-post design. A single group of software company employees (N = 120), age ≥30 years selected by simple random sampling was included in the study. The intervention consisted of a health education programme on the portion sizes of common food items including fruits and vegetables. A self-administered questionnaire was used to collect information on personal and sociodemographic details. Self-regulation on eating was assessed using the Self-Regulation of Eating Behaviour Questionnaire (SREBQ).Results:The mean age of the study participants was 27 ± 5 years. Most of the participants were males, i.e., 72 (60%). Of the total, 55 (47.8%) participants were obese and 18 (15.7%) were overweight. The median number of meals and snacks consumed by the participants was 3 (1–3) and 1 (1–2), respectively. The median (interquartile range [IQR]) knowledge scores of the food portion size significantly increased from 9 (0–16) to 14 (5–19) (P < 0.05).Conclusions:This study has demonstrated that an educational intervention in the workplace setting is feasible and effective in increasing the knowledge of food portion size over a short term.

Incorporating indirect pathways in body size-trophic position relationships.

Body size, trophic position (TP), and trophic niche width are important elements of food webs; however, there is still debate regarding their interrelationships. Most studies have tested these correlations using datasets restricted to carnivores and bivariate models that disregard potential indirect effects of other factors, their interactions, and phylogeny. We analyzed relationships among TP, consumer size, maximum food item size, food item size variation (a proxy for trophic niche width), and two other traits (gut length and mouth width) using confirmatory path analysis of an extensive dataset for freshwater fishes that encompass both carnivorous and non-carnivorous species. Consumer size was associated with maximum food size, food size variation, mouth width, and gut length, all of which mediated indirect relationships between body size and TP. Mouth gape was associated with maximum food size, and consumers that fed on larger food items had higher TP. Consumers with relatively long guts generally fed on small and homogeneous food items near the base of the food web. Models were consistent whether or not accounting for phylogeny, but varied according to trophic guilds. However, the body size of both carnivorous and non-carnivorous was not directly associated with TP. Therefore, the incorporation of functional traits and their intermediate pathways is critical for understanding size-based trophic relationships of animals that encompass diverse feeding strategies. Our results caution approaches that rely on body size as a surrogate for TP, especially in systems where plants and detritus are consumed directly by a significant number of animals, such as in most freshwater ecosystems.

How do patients with eating disorders perceive and evaluate food portion sizes? A systematic review.

The selection of adequate portion sizes plays a key role in the nutritional treatment of eating disorders (EDs). There is limited knowledge concerning the estimation of portion sizes in individuals with EDs. We performed a systematic review according to the PRISMA statement to synthesise current evidence in this field. Of N = 584 hits, four full-texts were included in the qualitative synthesis. While patients with anorexia nervosa (AN) tend to overestimate the size of energy-dense food items and small to medium sized meal portions, they do not show a different estimation compared to healthy controls when judging the amount of food pieces. Large portion sizes were associated with increased anxiety in patients with AN. The overestimation of food portion sizes seems to be driven by attitudinal and/or higher cognitive factors associated with AN. Differences between the studies are discussed and suggestions for future studies are given.

Food density and preferred quantity: discrimination of small and large numbers in angelfish (Pterophyllum scalare).

Many animal species share the ability to discriminate between sets with different quantity of food items. In fish, this ability has rarely been investigated, although findings have been obtained do indicate a preference, as in other animals, for sets with large over small quantities. The role played by food item size has also been found to be important in the discrimination. However, another potentially important non-numerical variable, food density, has not been investigated. In this study, we examined the influence of density (inter-item distance) in the decision-making process of food discrimination in angelfish (Pterophyllum scalare). In a binary choice task, we kept the number and size of food items constant, but contrasted a set containing food items spaced further apart (sparse set) to another set with food items spaced more closely (dense set). We conducted this analysis with sets in the small (3 vs 3 food items) and in the large number range (5 vs 5 food items) and also varied the specific spatial arrangements of the food items in the sets. Contrary to expectations, angelfish showed a preference for the sparse sets over the dense sets in the five vs five contrasts irrespective of the specific spatial arrangement, but exhibited no preference in case of the three vs three contrasts. Subsequently, we slightly lengthened the inter-item distance in the dense sets, and found preference for the dense over the sparse sets. Last, we further examined the potential effect of spatial configuration of the items in the sets, but found no effect of this latter factor. Overall, these results indicate that higher density of the contrasted food item sets significantly influences choice in angelfish, which prefer denser sets if a clear discriminability of each individual item within the sets is provided.

The relationship between dietary intakes during pregnancy and incidence of postpartum depression: a case-control study

PurposePost-partum depression (PPD) is a mood disorder that affects 20-40 per cent of women in their post-delivery period worldwide. The purpose of this paper is to compare dietary intakes of energy, macronutrients, cholesterol, saturated fatty acids (SFAs), mono-unsaturated fatty acids (MUFAs), poly-unsaturated fatty acids (PUFAs), some micronutrients and antioxidants in PPD patients with healthy controls.Design/methodology/approachThis case-control study was conducted on 163 women in postpartum period (81 PPD and 82 non-PPD) using Edinburgh questionnaire for the diagnosis of PPD. Dietary nutrients intake was assessed using 147-item semi-quantitative food frequency questionnaire (FFQ). Portion sizes of food items were converted to grams per day. Logistic regression models were used to estimate the association between tertiles of dietary intakes with the odds ratio (OR) of PPD.FindingsAccording to the fully adjusted model, highest tertile compared to lowest tertile dietary intake of SFAs [OR = 0.01; 95 per cent confidence interval (CI) = 0.00, 0.01, p = 0.001], MUFAs (OR = 0.01; 95 per cent CI = 0.00, 0.02, p < 0.001), total fats (OR = 0.01; 95 per cent CI =0.00, 0.01, p < 0.001) and cholesterol (OR = 0.06 ; 95 per cent CI = 0.01, 0.08, p < 0.001), thiamine (OR = 0.01; 95 per cent CI = 0.00, 0.01, p < 0.001), riboflavin (OR = 0.10; 95 per cent CI = 0.02, 0.39, p < 0.001), pyridoxine (OR = 0.03; 95 per cent CI =0.01, 0.32, p < 0.001), folate (OR = 0.01; 95 per cent CI = 0.00, 0.01, p < 0.001), cobalamine (OR = 0.01; 95 per cent CI = 0.00, 0.01, p < 0.001) , selenium (OR = 0.79 ; 95 per cent CI =1.36, 3.32, p < 0.001), iron (OR =0.68; 95 per cent CI = 0.24, 0.94, p < 0.001) and iodine (OR = 0.36; 95 per cent CI =1.10, 1.38, p < 0.001) had a protective effect on the incidence of PPD. Furthermore, higher intake of vitamin A and beta-cryptoxanthin can increase the incidence of PPD (OR =114.29; 95 per cent CI =17.85, 118.12, p < 0.001) and (OR = 4.85; 95 per cent CI = 1.49, 15.69, p = 0.015), respectively.Originality/valuePPD may have destructive effects on the relationship between mother and infant. Results of previous studies demonstrated nutrients are required for the synthesis of neurotransmitters and have biochemical role in the nervous system.

The role of item size on choosing contrasted food quantities in angelfish (Pterophyllum scalare)

Comparative studies on quantity discrimination in animals are important for understanding potential evolutionary roots of numerical competence. A previous study with angelfish has shown that they discriminate numerically different sets of same-sized food items and prefer the larger set. However, variables that covary with number were not controlled and choice could have been influenced by variables such as size or density of the food items rather than numerical attributes. Here using a recently developed approach, we examined whether contour length of the food items affects choice in a spontaneous binary choice task. In Experiment 1, a contrast of 1 vs. 1 food item was presented, but the ratio between the size (diameter) of the food items was varied. In Experiment 2, numerically different food sets were equated in overall size by increasing the size (diameter) of the items in the numerically small sets. In both Experiments, subjects showed a preference for the larger sized food items with a discrimination limit. These results show that item size plays a prominent role in foraging decisions in angelfish. Experiment 3 placed numerical and size attributes of the sets in conflict by presenting one larger-sized food item in the numerically smaller set that also had smaller overall size (diameter) of food items. Angelfish showed no preference in any of the contrasts, suggesting that they could not make optimal foraging decisions when these attributes were in conflict. Maximization of energy return is central to optimal foraging. Accordingly, here item size was also found to be a key feature of the sets, although the numerical attributes of the sets also influenced the choice.

DỊ HÌNH KÍCH THƯỚC GIỚI TÍNH VÀ SINH THÁI DINH DƯỠNG CỦA LOÀI CHÀNG XANH (Hylarana erythraea) Ở VÙNG PHÚ LỘC, TỈNH THỪA THIÊN HUẾ

The Common Green Frog, Hylarana erythraea (Schlegel, 1837), is an important species in both terrestrial and aquatic ecosystems. However, information on sexual size dimorphism (SSD) and the feeding ecology of this species in Vietnam is currently lacking. We used the stomach-flushing method to obtain food items from 223 stomach specimens. The results showed that the average snout-vent length was significantly larger in adult females than in adult males, with an SSD index of 0.57. The most important prey categories of H. erythraea were Coleoptera, unidentified insect larvae, Odonata, Orthoptera, and Araneae (occurrence frequency 65.45 %, representing 65.89 % of the number of items, and 81.04 % of the total volume). The mouth width and snout-vent length had significant effects on the prey size and on the volume of food items. However, air temperature and relative humidity did not have significant effects on the prey volume or size of individual food items. These results supported the hypothesis that “the mouth size is the limiting factor on the food size” in anuran species.

Individual guppies differ in quantity discrimination performance across antipredator and foraging contexts

The ability to discriminate between different quantities is useful to an animal since it allows adaptive decisions in several contexts. In humans, some individuals are generally better at solving different numerical and mathematical problems, but we currently ignore whether other species also show individual differences in quantitative abilities across different contexts. Aiming to investigate this possibility, we observed the performances of individual guppies (Poecilia reticulata) in an antipredator task that required the discrimination between shoals made of a different number of conspecifics (4 versus 6 fish) and, successively, in two foraging tasks that required the discrimination between different numbers of food items (4 versus 6 items) and food items with different sizes (0.67 ratio between the two surface areas). Overall, guppies achieved comparable performances in the discrimination of shoal size and food item size, but showed reduced accuracy in the discrimination between different numbers of food items. Performances of guppies were correlated between the discrimination of shoal size and food item size, suggesting the existence of individual differences in quantity discrimination abilities in different contexts in this species. Unexpectedly, this relationship was negative, and some guppies were better in the antipredator task, while others were better in the foraging task. Our results agree with the general trend of the literature on animals that suggests the existence of multiple cognitive functions whose activation are task specific, and also introduce the possibility that some of these functions are subject to constraints. In this work, we provided the first clear evidence of individual differences in the ability to solve quantity discriminations in a fish. Guppies were observed in three quantity discrimination tasks: recognising and joining the larger shoal of conspecifics among two options, a behaviour that confers protection from predators; selecting the larger number of food items between two sets; and selecting the food item with larger size. Guppies that were more accurate in the shoal size discrimination achieved lower scores in the food item size discrimination. Some individuals gain advantage from cognitive abilities that confer defence against predators, while other individuals from those abilities that improve foraging success.

More or less: spontaneous quantity discrimination in the domestic cat.

We examined spontaneous quantity discrimination in untrained domestic cats in three food choice experiments. In Experiment 1, we presented the cats with two different quantities of food in eight numerical combinations. Overall, the subjects chose the larger quantity more often than the smaller one, and significantly so when the ratio between the quantities was less than 0.5. In Experiment 2, we presented the cats with two pieces of food in four different size combinations. Again, subjects chose the larger piece above chance, although not in the combination where the largest item was presented. In Experiment 3, a subset of the cats was presented multiple times with two different quantities of food, which were hidden from view. In this case, the cats did not choose the larger quantity more often than the smaller one, suggesting that in the present experiments they mainly used visual cues when comparing quantities. We conclude that domestic cats are capable of spontaneously discriminating quantities when faced with different numbers or sizes of food items, and we suggest why they may not always be motivated to choose the larger quantity. In doing so, we highlight the advantages of testing spontaneous choice behavior, which is more likely to reflect animals' everyday manner of responding than is the case when training them in order to test their absolute limits of performance which may not always coincide with their daily needs.

On the Relationship Between Tooth Shape and Masticatory Efficiency: A Finite Element Study.

Dental topography has successfully linked disparate tooth shapes to distinct dietary categories, but not to masticatory efficiency. Here, the relationship between four dental topographic metrics and brittle food item breakdown efficiency during compressive biting was investigated using a parametric finite element model of a bunodont molar. Food item breakdown efficiency was chosen to represent masticatory efficiency as it isolated tooth-food item interactions, where most other categories of masticatory efficiency include several aspects of the masticatory process. As relative food item size may affect the presence/absence of any relationship, four isometrically scaled, hemispherical, proxy food items were considered. Topographic metrics were uncorrelated to food item breakdown efficiency irrespective of relative food item size, and dental topographic metrics were largely uncorrelated to one another. The lack of a correlation between topographic metrics and food item breakdown efficiency is not unexpected as not all food items break down in the same manner (e.g., nuts are crushed, leaves are sheared), and only one food item shape was considered. In addition, food item breakdown efficiency describes tooth-food item interactions and requires location and shape specific information, which are absent from dental topographic metrics. This makes it unlikely any one efficiency metric will be correlated to all topographic metrics. These results emphasize the need to take into account how food items break down during biting, ingestion, and mastication when investigating the mechanical relationship between food item shape, size, mechanical properties, and breakdown, and tooth shape.

Smoke and mirrors: Testing the scope of chimpanzees’ appearance–reality understanding

The ability to make appearance–reality (AR) discriminations is an important higher-order cognitive adaptation in humans but is still poorly understood in our closest primate relatives. Previous research showed that chimpanzees are capable of AR discrimination when choosing between food items that appear, due to the effects of distorting lenses, to be smaller or larger than they actually are (Krachun, Call, & Tomasello, 2009). In the current study, we investigated the scope and flexibility of chimpanzees’ AR discrimination abilities by presenting them with a wider range of illusory stimuli. In addition to using lenses to change the apparent size of food items (Experiment 1), we used a mirror to change the apparent number of items (Experiment 2), and tinted filters to change their apparent color (Experiment 3). In all three experiments, some chimpanzees were able to maximize their food rewards by making a choice based on the real properties of the stimuli in contrast to their manifest apparent properties. These results replicate the earlier findings for size illusions and extend them to additional situations involving illusory number and color. Control tests, together with findings from previous studies, ruled out lower-level explanations for the chimpanzees’ performance. The findings thus support the hypothesis that chimpanzees are capable of making AR discriminations with a range of illusory stimuli.

Habitat complexity and food item size modify the foraging behaviour of a freshwater fish

The functional response describes the relationship between feeding rate and prey density, and is important ecologically as it describes how foraging behaviour may change in response to food availability. The effects of habitat complexity and food item size were experimentally tested on the foraging parameters and functional responses of the freshwater fish roach Rutilus rutilus. Habitat complexity was varied through the manipulation of substrate and turbidity, and food item size was varied by using fishmeal pellets in two sizes. As water turbidity and substrate complexity increased, the reaction distance and consumption rate (per number) significantly decreased. Increased food item size significantly decreased consumption rates (per number) but had no influence on any other foraging parameter. Analysis of the interactions between substrate complexity, turbidity and food item size revealed food item size had the greatest influence on consumption rate (per number). Turbidity had the least effect on all the foraging parameters tested. Across all experiments, the functional responses were best described by the Type II response, a relatively consistent finding for R. rutilus. These outputs reveal that fish foraging behaviours and functional responses are highly context dependent, varying with environmental parameters and the availability of food resources of different sizes.