The rewarding effects of number and surface area of food in rats.

Visual cues have an important role in food preference for both rats and humans. Here, we aim to isolate the effects of numerosity, density, and surface area on food preference and running speed in rats, by using a forced-choice maze paradigm. In Experiment 1, rats preferred and ran faster for a group of multiple smaller pellets rather than a single large pellet, corroborating previous research (Capaldi, Miller, & Alptekin Journal of Experimental Psychology: Animal Behavior Processes, 15(1), 75-80, 1989). Further experiments tested the prevailing hypothesis that multiple food pieces are more reinforcing because they occupy a larger surface area. Experiment 2 controlled for numerosity by utilizing a continuous food: mashed potatoes flattened to cover a larger surface area or rounded into a ball. The rats preferred and ran faster for the flattened potatoes, suggesting surface area plays a role in quantity estimations. Finally, in Experiment 3, rats displayed no preference or difference in running speed between a group of scattered and clustered pellets when number of pellets were kept constant. Taken together, these results suggest that density has an important role in food perception-that is, the rewarding effect of higher numerosity or larger surface area is removed when the food does not fill out the entire space. Alternative explanations and implications for human diet are discussed.

Axial or Helical? Considerations for wide collimation CT scanners capable of volumetric imaging in both modes.

PURPOSE: To determine whether axial or helical mode is more appropriate for a 16 cm collimation CT scanner capable of step-and-shoot volumetric axial coverage, in terms of radiation dose, image quality, and scan duration. METHODS: All scans were performed with a Revolution CT (GE Healthcare) operating at 120 kV and 100 mAs. Using calibrated optically stimulated luminescence detectors, radiation dose along the axial scan profile was evaluated at the isocenter, including the overlap region between two axial sections. This overlap region measures 3 cm in the z-axis at the isocenter and is required to obtain sufficient projection data from the relatively large cone-beam angles. Using an image quality phantom (Gammex Model 464), spatial resolution, CT number uniformity, image noise, and low contrast detectability (LCD) were evaluated under five different conditions: in the middle of a helical acquisition, in the middle of a 16 cm axial section, at both ends of an axial section and in the overlap region between two axial sections. Scan durations and dose length products (DLP) were recorded for prescribed scan lengths of 2.5-100 cm. RESULTS: The overlap region between two axial sections received a dose 83% higher than the single-exposure region at the isocenter. Within a single axial section, the dose at the anode end was 37% less than at the cathode end due to the anode heel effect. Image noise ranged from a low of 13 HU for the cathode end of an axial section up to 14.7 HU for the anode end (P < 0.001). The LCD was at lower at the anode end of the axial section compared to both the cathode end (P < 0.05) and the overlap location (P < 0.02). The spatial resolution and CT number uniformity were consistent among all conditions. Scan durations were shorter (0.28 s) for the axial mode compared to the helical mode at scan lengths ≤ 16 cm, and longer at scan lengths ≥ 16 cm where more than one table position was required, up to a difference of 13.9 s for a the 100 cm scan length (3.8 s for helical compared to 17.6 s for axial). DLPs were consistent between scan modes; slightly lower in axial mode at shorter scan lengths due to helical overranging, and slightly higher in axial mode at longer scan lengths due to the axial overlap regions. CONCLUSIONS: To ensure the most consistent radiation dose and image quality along the scan length, we recommend helical mode for scans longer than the 16 cm coverage of a single axial section. For scan lengths ≤ 16 cm, axial scanning is the most practical option, with a shorter scan duration and higher dose efficiency.

Modeling eating behaviors: The role of environment and positive food association learning via a Ratatouille effect.

Eating behaviors among a large population of children are studied as a dynamic process driven by nonlinear interactions in the sociocultural school environment. The impact of food association learning on diet dynamics, inspired by a pilot study conducted among Arizona children in Pre-Kindergarten to 8th grades, is used to build simple population-level learning models. Qualitatively, mathematical studies are used to highlight the possible ramifications of instruction, learning in nutrition, and health at the community level. Model results suggest that nutrition education programs at the population-level have minimal impact on improving eating behaviors, findings that agree with prior field studies. Hence, the incorporation of food association learning may be a better strategy for creating resilient communities of healthy and non-healthy eaters. A Ratatouille effect can be observed when food association learners become food preference learners, a potential sustainable behavioral change, which in turn, may impact the overall distribution of healthy eaters. In short, this work evaluates the effectiveness of population-level intervention strategies and the importance of institutionalizing nutrition programs that factor in economical, social, cultural, and environmental elements that mesh well with the norms and values in the community.

Teaching children to like and eat vegetables.

Higher vegetable intake has been related to lower risks of diabetes, cardiovascular disease, several cancers and obesity. Yet children consume fewer than the recommended servings of fruits and vegetables set forth by the USDA. Exposure to vegetables has successfully improved children's liking for and consumption of vegetables particularly for children younger than two years. In contrast, associative conditioning seems necessary for older children, especially with bitter vegetables. We review studies using both exposure and associative conditioning to teach children to like vegetables, including flavor-flavor learning and flavor-calorie learning. Recognizing these different processes helps reconcile discrepant literature and may provide techniques for increasing preferences for vegetables in children. Associative conditioning and exposure can be used by parents and others to enhance children's liking for and consumption of vegetables.

Perceived recollection of frequent exposure to foods in childhood is associated with adulthood liking.

Food preferences and habits learned at a young age can influence adulthood dietary patterns and weight, but the mechanism remains to be elucidated. We investigated the effect of perceived recollections of early food experiences on current liking for those foods by 670 college students. We showed that the perceived recollection of frequent consumption of foods in childhood was significantly related to current liking for the vast majority of the foods, including nutritious foods such as vegetables. Similarly, parental encouragement and modeling was positively related with current liking, even for foods that were disliked in childhood. Additionally, perceived recollections of parental restriction or forced consumption were significantly negatively related with current liking. Lastly, we demonstrated that perceived recollections by college students of childhood eating practices were in moderate agreement with those of their parents, lending credibility to the retrospective survey methodology in determining long-term effects of exposure on current food habits. These findings show that the perceived recalled frequency of consumption of foods is one determinant of the food preferences of adults, demonstrating a long-term effect of frequency of exposure, a finding consistent with experimentally controlled short-term studies. Frequent exposure to foods in childhood could be a simple and effective way for parents and caregivers to instill healthy eating habits in children.

Heterogeneous binary interactions of taste primaries: perceptual outcomes, physiology, and future directions.

Complex taste experiences arise from the combinations of five taste primaries. Here we review the literature on binary interactions of heterogeneous taste primaries, focusing on perceptual results of administering mixtures of aqueous solutions to human participants. Some interactions proved relatively consistent across tastants and experimental methods: sour acids enhanced saltiness, salts and sweeteners suppressed bitterness, sweeteners suppressed sourness, and sour acids enhanced bitterness. However, for the majority of interactions there were differential effects based on the tastants and their concentrations. Drawing conclusions about interactions with umami is currently not possible due to the low number of primary source studies investigating it and the confounding sodium ions in monosodium glutamate (MSG). Speculative physiological explanations are provided that fit the current data and suggestions for future research studies are proposed.

A review of visual cues associated with food on food acceptance and consumption.

Several sensory cues affect food intake including appearance, taste, odor, texture, temperature, and flavor. Although taste is an important factor regulating food intake, in most cases, the first sensory contact with food is through the eyes. Few studies have examined the effects of the appearance of a food portion on food acceptance and consumption. The purpose of this review is to identify the various visual factors associated with food such as proximity, visibility, color, variety, portion size, height, shape, number, volume, and the surface area and their effects on food acceptance and consumption. We suggest some ways that visual cues can be used to increase fruit and vegetable intake in children and decrease excessive food intake in adults. In addition, we discuss the need for future studies that can further establish the relationship between several unexplored visual dimensions of food (specifically shape, number, size, and surface area) and food intake.

Associative conditioning can increase liking for and consumption of brussels sprouts in children aged 3 to 5 years.

Pairing foods with liked flavors repeatedly can increase preferences for those foods. We compared the effectiveness of associative conditioning (pairing vegetables with sweetened and unsweetened cream cheese) and exposure (presenting vegetables alone) in increasing liking and consumption of bitter and nonbitter vegetables. Twenty-nine children (aged 3 to 5 years) participated in the study. One group of children received brussels sprouts (bitter) with sweetened cream cheese and cauliflower (nonbitter) with unsweetened cream cheese and a second group received the reverse pairing. A third group received brussels sprouts and cauliflower with no cream cheese. Pairing brussels sprouts with cream cheese increased liking and consumption more than exposure, whereas cauliflower was liked by all groups regardless of presence of cream cheese. Associative conditioning was more effective than exposure in increasing liking for a novel, bitter vegetable-brussels sprouts-whereas exposure alone was effective for a nonbitter, more familiar vegetable-cauliflower.