This work was supported by grants to J.C. Snow from the National Eye Institute of the National Institutes of Health (NIH) under Award Number R01EY026701, the National Science Foundation (NSF) [grant 1632849] and the Clinical Translational Research Infrastructure Network [grant 17-746Q-UNR-PG53-00]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH, NSF or CTR-IN.

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The authors have nothing to disclose.

The overarching goal of the current paper is to facilitate future studies of &#39;real world&#39;&#160;object vision by providing detailed information about how to present large numbers of real-world objects (and images) under controlled experimental conditions. We present an ecologically-valid approach for studying the factors that influence dietary choice and food valuation. We describe methods employed in a recent study of human decision-making7 in which we examined whether snack foods presente...

The translational value of primary research in human perception and cognition hinges on the extent to which the findings transfer to real-world stimuli and contexts. A long-standing question concerns how the brain processes real-world sensory inputs. Currently, knowledge of visual cognition is based almost exclusively on studies that have relied on stimuli in the form of two-dimensional (2-D) pictures, usually presented in the form of computerized images. Although image interaction is becoming increasingly common in the modern world, humans are active observers for whom the visual system has evolved to allow perception and interaction with real objects, not images1. To date, the overarching assumption in studies of human vision has been that images are equivalent to, and appropriate proxies for, real object displays. Currently, however, we know surprisingly little about whether images effectively trigger the same underlying cognitive processes as do the real objects. Therefore, it is important to determine the extent to which responses to images are like, or different from, those elicited by their real-world counterparts.
There are several important differences between real objects and images that could lead to differences in how these stimuli are processed in the brain. When we look at real objects with two eyes, each eye receives information from a slightly different horizontal vantage point. This discrepancy between the different images, known as binocular disparity, is resolved by the brain to produce a unitary sense of depth2,3. Depth cues derived from stereoscopic vision, together with other sources such as motion parallax, convey precise information to the observer about the object&#8217;s egocentric distance, location, and physical size, as well its three-dimensional (3-D) geometric shape structure4,5. Planar images of objects do not convey information about the physical size of the stimulus because only the distance to the monitor is known by the observer, not the distance to the object. While 3-D images of objects, such as stereograms, approximate more closely the visual appearance of real objects, they do not exist in 3-D space, nor do they afford genuine motor actions such as grasping with the hands6.
The practical challenges of using real object stimuli in experimental contexts 
Unlike studies of the image vision in which stimulus presentation is entirely computer-controlled, working with real objects presents a range of practical challenges for the experimenter. The position, order, and timing of object presentations must be controlled manually throughout the experiment. Working with real objects (unlike images) can involve a significant time commitment due to the need to collect7,8,9 or make10 the objects, set up the stimuli prior to the experiment, and present the objects manually during the study. Moreover, in experiments that are designed to compare, directly, responses to real objects with images, it is critical to match closely the appearance of the stimuli in the different display formats8,9. Stimulus parameters, environmental conditions, as well as randomization and counterbalancing of real object and image stimuli, must all be controlled carefully to isolate causal factors and rule out alternative explanations for the observed effects.
The methods detailed below for presenting real objects (and matched images) are described in the context of a decision-making paradigm. The general approach can be extended, however, to examine whether stimulus format influences other aspects of visual cognition such as perception, memory or attention.
Are real objects processed differently to images? A case example from decision-making 
The mismatch between the kinds of objects that we encounter in real-world scenarios versus those examined in laboratory experiments is especially apparent in studies of human decision-making. In most studies of dietary choice, participants are asked to make judgments about snack foods that are presented as colored 2-D images on a computer monitor 11,12,13,14. In contrast, everyday decisions about which foods to eat are usually made in the presence of real foods, such as at the supermarket or the cafeteria. Although in modern life we regularly view images of snack foods (i.e., on billboards, television screens and online platforms), the ability to detect and respond appropriately to the presence of real energy-dense foods may be adaptive from an evolutionary perspective because it facilitates growth, competitive advantage, and reproduction15,16,17.
Research outcomes in scientific studies of decision-making and dietary choice have been used to guide public health initiatives aimed at curbing rising obesity rates. Unfortunately, however, these initiatives appear to have met with little to no measurable success18,19,20,21. Obesity remains a major contributor to the global burden of a disease22 and is linked to a range of associated health problems, including coronary heart disease, dementia, Type II diabetes, certain cancers, and increased overall risk of morbidity22,23,24,25,26,27. The sharp rise in obesity and associated health conditions over recent decades28 has been linked with the availability of cheap, energy-dense foods18,29. As such, there is an intense scientific interest in understanding the underlying cognitive and neural systems that regulate everyday dietary decisions.
If there are differences in the way foods in different formats are processed in the brain, then this might provide insights into why public health approaches to combating obesity have been unsuccessful. Despite the differences between images and real-world objects, described above, surprisingly little is known about whether images of snack foods are processed similarly to their real-world counterparts. In particular, little is known about whether or not real foods are perceived to be more valuable or satiating than matched images of the same items. Classic early behavioral studies found that young children were able to delay gratification in the context of 2-D colored images of snack foods30, but not when they were confronted with real snack foods31. However, few studies have examined in adults whether the format in which a snack food is displayed influences decision-making or valuation12,32,33 and only one study to date, from our laboratory, has tested this question when stimulus parameters and environmental factors are matched across formats7. Here, we describe innovative techniques and apparatus for investigating whether decision-making in healthy human observers is influenced by the format in which the stimuli are displayed.
Our study7 was motivated by a previous experiment conducted by Bushong and colleagues12 in which college-aged students were asked to place monetary bids on a range of everyday snack foods using a Becker-DeGroot-Marschak (BDM) bidding task34. Using a between-subjects design, Bushong and colleagues12 presented the snack foods in one of three formats: text descriptors (i.e., &#39;Snickers bar&#39;), 2-D colored images, or real foods. Average bids for the snacks (in dollars) were contrasted across the three participant groups. Surprisingly, students who viewed real foods were willing to pay 61% more for the items than those who viewed the same stimuli as images or text descriptors -a phenomenon the authors termed the &#39;real-exposure effect&#39;12. Critically, however, participants in the text and image conditions completed the bidding task in a group setting and entered their responses via individual computer terminals; conversely, those assigned to the real food condition performed the task one-on-one with the experimenter. The appearance of the stimuli in the real and image conditions was also different. In the real food condition, the foods were presented to the observer on a silver tray, whereas in the image condition the stimuli were presented as scaled cropped images on a black background. Thus, it is possible that participant differences, environmental conditions, or stimulus-related differences, could have led to inflated bids for the real foods. Following from Bushong, et al.12, we examined whether the real foods are valued more than 2-D images of food, but critically, we used a within-subjects design in which environmental and stimulus-related factors were carefully controlled. We developed a custom-designed turntable in which the stimuli in each display format could be interleaved randomly from trial to trial. Stimulus presentation and timing were identical across the real object and image trials, thus reducing the likelihood that participants could use different strategies to perform the task in the different display conditions. Finally, we controlled carefully the appearance of the stimuli in the real object and image conditions so that the real foods and images were matched closely for apparent size, distance, viewpoint, and background. There are likely to be other procedures or mechanisms that could allow for randomizing stimulus formats across trials, but our method allows for many objects (and images) to be presented in relatively rapid interleaved succession. From a statistical standpoint, this design maximizes power to detect significant effects more so than is possible using between-subjects designs. Similarly, the effects cannot be attributed to a-priori differences in willingness-to-pay (WTP) between observers. It is, of course, the case that in within-subjects designs open the possibility for demand characteristics. However, in our study participants understood that they could &#39;win&#39;&#160;a food item at the end of the experiment regardless of the display format in which it appeared in the bidding task. Participants were also informed that arbitrarily reducing bids (i.e., for the images) would reduce their chances of winning and that the best strategy for winning the desired item is to bid one&#8217;s true value34,35,36. The aim of this experiment is to compare WTP for real foods versus 2-D images using a BDM bidding task34,35.

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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">EOS Rebel T2i Body Camera</td>
			<td style="width:139px;">Canon&#160;</td>
			<td style="width:119px;">4462B001</td>
			<td style="width:611px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">MATLAB</td>
			<td style="width:139px;">MathWorks&#160;</td>
			<td>R2017b</td>
			<td>Computer programming software. Download this additional free toolbox: PsychToolbox 3.0.14</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Photoshop</td>
			<td style="width:139px;">Adobe</td>
			<td>CS6</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">PLATO Visual Occlusion Glasses</td>
			<td style="width:139px;">Translucent Technologies Inc.&#160;</td>
			<td style="width:119px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">SPSS</td>
			<td style="width:139px;">IBM</td>
			<td style="width:119px;">Version 22</td>
			<td>Statitical analysis software</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">ToTaL Control System (USB)</td>
			<td style="width:139px;">Translucent Technologies Inc.&#160;</td>
			<td style="width:119px;">N/A</td>
			<td style="width:611px;">The ToTaL Control System&#160; controls the&#160;PLATO&#160;spectacles</td>
		</tr>
	</tbody>
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methods for presenting real-world objects under controlled laboratory conditions

Our knowledge of human object vision is based almost exclusively on studies in which the stimuli are presented in the form of computerized two-dimensional (2-D) images. In everyday life, however, humans interact predominantly with real-world solid objects, not images. Currently, we know very little about whether images of objects trigger similar behavioral or neural processes as do real-world exemplars. Here, we present methods for bringing the real-world into the laboratory. We detail methods for presenting rich, ecologically-valid real-world stimuli under tightly-controlled viewing conditions. We describe how to match closely the visual appearance of real objects and their images, as well as novel apparatus and protocols that can be used to present real objects and computerized images on successively interleaved trials. We use a decision-making paradigm as a case example in which we compare willingness-to-pay (WTP) for real snack foods versus 2-D images of the same items. We show that WTP increases by 6.6% for food items displayed as real objects versus high-resolution 2-D colored&#160;images of the same foods -suggesting that real foods are perceived as being more valuable than their images. Although presenting real object stimuli under controlled conditions presents several practical challenges for the experimenter, this approach will fundamentally expand our understanding of the cognitive and neural processes that underlie naturalistic vision.

Representative results from this experiment are presented below. A more detailed description of the results, together with a follow-up study, can be found in the original publication7. We used a linear mixed effects model with the dependent variable of Bid, and independent variables of Display Format, Preference, Caloric Density, and Estimated Calories. As expected, and in line with previous studies12,14, there was a strong positive relati...

Watch this Scientific Journal Video about Methods for Presenting Real-world Objects Under Controlled Laboratory Conditions at JoVE.com

Methods for Presenting Real-world Objects Under Controlled Laboratory Conditions

We describe methods for presenting real-world objects and matched images of the same objects under tightly-controlled experimental conditions. The methods are described in the context of a decision-making task, but the same real-world approach can be extended to other cognitive domains such as perception, attention, and memory.

Our knowledge of human object vision is based almost exclusively on studies in which the stimuli are presented in the form of computerized two-dimensional ...

methods-for-presenting-real-world-objects-under-controlled-laboratory

Research

JoVE Journal

Behavior

5.8K Views.  University of Nevada, Reno. We describe methods for presenting real-world objects and matched images of the same objects under tightly-controlled experimental conditions. The methods are described in the context of a decision-making task, but the same real-world approach can be extended to other cognitive domains such as perception, attention, and memory.

Video: Methods for Presenting Real-world Objects Under Controlled Laboratory Conditions

Methods to Test Visual Attention Online

Online data collection methods have particular appeal to behavioral scientists because they offer the promise of much larger and much more representative data samples than can typically be collected on college campuses. However, before such methods can be widely adopted, a number of technological challenges must be overcome &#8211; in particular in experiments where tight control over stimulus properties is necessary. Here we present methods for collecting performance data on two tests of visual attention. Both tests require control over the visual angle of the stimuli (which in turn requires knowledge of the viewing distance, monitor size, screen resolution, etc.) and the timing of the stimuli (as the tests involve either briefly flashed stimuli or stimuli that move at specific rates). Data collected on these tests from over 1,700 online participants were consistent with data collected in laboratory-based versions of the exact same tests. These results suggest that with proper care, timing/stimulus size dependent tasks can be deployed in web-based settings.

To replicate laboratory settings, online data collection methods for visual tasks require tight control over stimulus presentation. We outline methods for the use of a web application to collect performance data on two tests of visual attention.

Online data collection methods have particular appeal to behavioral scientists because they offer the promise of much larger and much more representative ...

Using Fiberless, Wearable fNIRS to Monitor Brain Activity in Real-world Cognitive Tasks

Functional Near Infrared Spectroscopy (fNIRS) is a neuroimaging technique that uses near-infrared light to monitor brain activity. Based on neurovascular coupling, fNIRS is able to measure the haemoglobin concentration changes secondary to neuronal activity. Compared to other neuroimaging techniques, fNIRS represents a good compromise in terms of spatial and temporal resolution. Moreover, it is portable, lightweight, less sensitive to motion artifacts and does not impose significant physical restraints. It is therefore appropriate to monitor a wide range of cognitive tasks (e.g., auditory, gait analysis, social interaction) and different age populations (e.g., new-borns, adults, elderly people). The recent development of fiberless fNIRS devices has opened the way to new applications in neuroscience research. This represents a unique opportunity to study functional activity during real-world tests, which can be more sensitive and accurate in assessing cognitive function and dysfunction than lab-based tests. This study explored the use of fiberless fNIRS to monitor brain activity during a real-world prospective memory task. This protocol is performed outside the lab and brain haemoglobin concentration changes are continuously measured over the prefrontal cortex while the subject walks around in order to accomplish several different tasks.

Monitoring brain activity outside the lab without physical constraints presents methodological challenges. A fiberless, wearable functional Near Infrared Spectroscopy (fNIRS) system was used to measure brain activity during an ecological prospective memory task. It was demonstrated that this system could be used to monitor brain activity during non-lab based experiments.

Functional Near Infrared Spectroscopy (fNIRS) is a neuroimaging technique that uses near-infrared light to monitor brain activity. Based on neurovascular ...

Introducing Clicker Training as a Cognitive Enrichment for Laboratory Mice

Establishing new refinement strategies in laboratory animal science is a central goal in fulfilling the requirements of Directive 2010/63/EU. Previous research determined a profound impact of gentle handling protocols on the well-being of laboratory mice. By introducing clicker training to the keeping of mice, not only do we promote the amicable treatment of mice, but we also enable them to experience cognitive enrichment. Clicker training is a form of positive reinforcement training using a conditioned secondary reinforcer, the "click" sound of a clicker, which serves as a time bridge between the strengthened behavior and an upcoming reward. The effective implementation of the clicker training protocol with a cohort of 12 BALB/c inbred mice of each sex proved to be uncomplicated. The mice learned rather quickly when challenged with tasks of the clicker training protocol, and almost all trained mice overcame the challenges they were given (100% of female mice and 83% of male mice). This study has identified that clicker training for mice strongly correlates with reduced fear in the mice during human-mice interactions, as shown by reduced anxiety-related behaviors (e.g., defecation, vocalization, and urination) and fewer depression-like behaviors (e.g., floating). By developing a reliable protocol that can be easily integrated into the daily routine of the keeping of laboratory mice, the lifetime experience of welfare in the mice can be improved substantially.

The development of new refinement strategies for laboratory mice is a challenging task that contributes towards fulfilling the 3R principle. This protocol introduces clicker training as a cognitive enrichment program for laboratory mice.

Establishing new refinement strategies in laboratory animal science is a central goal in fulfilling the requirements of Directive 2010/63/EU. Previous ...

A Real-world What-Where-When Memory Test

Episodic memory is a complex memory system which allows recall and mental re-experience of previous episodes from one&#39;s own life. Real-life episodic memories are about events in their spatiotemporal context and are typically visuospatial, rather than verbal. Yet often, tests of episodic memory use verbal material to be recalled (word lists, stories). The Real-World What-Where-When memory test requires participants to hide a total of 16 different objects in 16 different locations over two temporal occasions, 2 h apart. Another two hours later, they are then asked to recall which objects (What) they had hidden in which locations (Where) and on which of the two occasions (When). In addition to counting the number of correctly recalled complete what-where-when combinations, this task can also be used to test real-world spatial memory and object memory. This task is sensitive to normal cognitive aging, and correlates well with performance on other episodic memory tasks, while at the same time providing more ecological validity and being cheap and easy to run.

A Real-world What-Where-When Memory Test

The Real-World What-Where-When memory test is a novel episodic memory test, in which participants need to recall which objects have been hidden in which locations on which of two distinct occasions. It is easy to run and is sensitive to normal cognitive aging.

Episodic memory is a complex memory system which allows recall and mental re-experience of previous episodes from one&#39;s own life. Real-life episodic ...

Basic Methods for the Study of Reproductive Ecology of Fish in Aquaria

Captive-rearing observations are valuable for revealing aspects of fish behavior and ecology when continuous field investigations are impossible. Here, a series of basic techniques are described to enable observations of the reproductive behavior of a wild-caught gobiid fish, as a model, kept in an aquarium. The method focuses on three steps: collection, transport, and observations of reproductive ecology of a substrate spawner. Essential aspects of live fish collection and transport are (1) preventing injury to the fish, and (2) careful acclimation to the aquarium. Preventing harm through injuries such as scratches or a sudden change of water pressure is imperative when collecting live fish, as any physical damage is likely to negatively affect the survival and later behavior of the fish. Careful acclimation to aquaria decreases the incidence death and mitigates the shock of transport. Observations during captive rearing include (1) the identification of individual fish and (2) monitoring spawned eggs without negative effects to the fish or eggs, thereby enabling detailed investigation of the study species' reproductive ecology. The subcutaneous injection of a visible implant elastomer (VIE) tag is a precise method for the subsequent identification of individual fish, and it can be used with a wide size range of fish, with minimal influence on their survival and behavior. If the study species is a substrate spawner that deposits adhesive eggs, an artificial nest site constructed from polyvinyl chloride (PVC) pipe with the addition of a removable waterproof sheet will facilitate counting and monitoring the eggs, lessening the investigator's influence on the nest-holding and egg-guarding behavior of the fish. Although this basic method entails techniques that are seldom mentioned in detail in research articles, they are fundamental for undertaking experiments that require the captive rearing of a wild fish.

A series of basic methods to enable the study of the reproductive ecology of fish kept in aquaria are described. These are useful protocols for collecting fish using SCUBA, transporting live fish, and observing the reproductive behavior of wild-caught fish kept in aquaria.

Captive-rearing observations are valuable for revealing aspects of fish behavior and ecology when continuous field investigations are impossible. Here, a ...

Methods of Pairing and Pair Maintenance of New Zealand White Rabbits (Oryctolagus Cuniculus) Via Behavioral Ethogram, Monitoring, and Interventions

New Zealand White (NZW) laboratory rabbits (Oryctolagus cuniculus), as well as their ancestors the European Rabbit, are a social species that exhibit numerous benefits to being housed accordingly. Although these rabbits are innately gregarious, certain behaviors can still arise when kept in captivity, which if left unchecked, can confound research results or lead to wounding, which in extreme cases can be severe. To prevent these issues, there must be a well-structured plan for the monitoring and maintenance of paired laboratory rabbits. The purpose of this protocol is to present effective procedures for establishing newly paired NZW rabbits as well as methods for successful maintenance. Multiple methods have been tested for the creation of newly paired female rabbits from the vendor, but the most efficacious technique emphasizes capitalizing on the stress bonding from transport, urine marking, pairing in a neutral cage with no forced sharing of resources and a system of monitoring and intervention. To determine the best method of housing paired rabbits in a standard caging environment, data were collected to generate a behavioral ethogram. Behaviors were then quantified as positive, neutral or negative and were tracked across the lifespan of the pair to determine which behaviors indicated pair success or failure. With the newfound knowledge of socially housed laboratory NZW rabbit behavior, enrichment intervention was applied to alleviate aggression and prevent wounding, thus resulting in a higher percentage of successful pairs. Through several years of trialing different pairing methods, the development of the ethogram and the resulting enrichment interventions, understanding of the highly complex social constructs that dominate pair housed rabbit behavior has dramatically increased and allowed for the provision of more species-specific care and increased standards of welfare.

Methods of Pairing and Pair Maintenance of New Zealand White Rabbits Oryctolagus Cuniculus Via Behavioral Ethogram, Monitoring, and Interventions

Though European rabbits are a social species, socially housing them can be challenging. Therefore, there must be a thorough understanding of behaviors and social structures of pair-housed laboratory rabbits. Here we present a protocol to identify pairing methods, species-typical hierarchy establishment behaviors and behaviors that warrant appropriate intervention.

New Zealand White (NZW) laboratory rabbits (Oryctolagus cuniculus), as well as their ancestors the European Rabbit, are a social species that exhibit ...

Noninvasive, In-pen Approach Test for Laboratory-housed Pigs

Traumatic brain injury (TBI) incidences have increased in both civilian and military populations, and many researchers are adopting a porcine model for TBI. Unlike rodent models for TBI, there are few behavioral tests that have been standardized. A larger animal requires more invasive handling in test areas than rodents, which potentially adds stress and variation to the animals&#39; responses. Here, the human approach test (HAT) is described, which was developed to be performed in front of laboratory pigs&#39; home pen. It is noninvasive, but flexible enough that it allows for differences in housing set-ups.
During the HAT, three behavioral ethograms were developed and then a formula was applied to create an approach index (AI). Results indicate that the HAT and its index, AI, are sensitive enough to detect mild and temporary alterations in pigs&#39; behavior after a mild TBI (mTBI). In addition, although specific behavior outcomes are housing-dependent, the use of an AI reduces variation and allows for consistent measurements across laboratories. This test is reliable and valid; HAT can be used across many laboratories and for various types of porcine models of injury, sickness, and distress. This test was developed for an optimized manual timestamping method such that the observer consistently spends no more than 9 min on each sample.

This protocol describes a new behavioral test&#8212;the human approach test in the pigs&#39; home pen&#8212;to detect functional deficits in laboratory pigs after subconcussive traumatic brain injury.

Traumatic brain injury (TBI) incidences have increased in both civilian and military populations, and many researchers are adopting a porcine model for ...

Three Laboratory Procedures for Assessing Different Manifestations of Impulsivity in Rats

The present article provides a guide for the conduction and analysis of three conditioning-based protocols to evaluate impulsivity in rats. Impulsivity is a meaningful concept because it is associated with psychiatric conditions in humans and with maladaptive behavior in non-human animals. It is believed that impulsivity is composed of separate factors. There are laboratory protocols devised to assess each of these factors using standardized automated equipment. Delay discounting is associated with the incapacity to be motivated by delayed outcomes. This factor is evaluated through intertemporal choice protocols, which consist&#160;of presenting the individual with a choice situation involving an immediate reward and a larger but delayed reward. Response inhibition deficit is associated with the incapacity to withhold prepotent responses. Differential reinforcement of low rates (DLR) and feature-negative discrimination protocols assess the response inhibition deficit factor of impulsivity. The former imposes a condition to a motivated individual in which most wait a minimum period of time for a response to be rewarded. The latter evaluates the capacity of individuals to refrain from food seeking responses when a signal of the absence of food is presented. The purpose of these protocols is to construct an objective quantitative measure of impulsivity, which serves to make cross-species comparisons, allowing the possibility of translational research. The advantages of these particular protocols include their easy set-up and application, which stems from the relatively small amount of equipment needed and the automated nature of these protocols.

We present three protocols that assess different forms of impulsivity in rats and other small mammals. Intertemporal choice procedures evaluate the tendency to discount the value of delayed outcomes. Differential reinforcement of low rates and feature-negative discrimination evaluate response inhibition capacity with and without punishment for inappropriate responses, respectively.

The present article provides a guide for the conduction and analysis of three conditioning-based protocols to evaluate impulsivity in rats. Impulsivity is ...

Generating Strictly Controlled Stimuli for Figure Recognition Experiments

This protocol introduces a method for generating strictly controlled and objectively defined stimuli for figure recognition experiments. A (6, n) figure consists of n line segments that are spanned between n pairs of points located at the vertices of an invisible regular hexagon. The structural properties (graph invariants) and superficial features (non-graph invariants) of each (6, n) figure with n values ranging from 1 to 6 are calculated and stored in a database. Using this database, experimenters can systematically extract appropriate figures depending on the purpose of the experiment. Furthermore, if the database does not contain necessary information, new feature values can sometimes be calculated ad hoc from the formation of a specific (6, n) figure. Let us call a mirror-reflected pair of figures an axisymmetric (Ax) pair. An Ax pair of figures is known to be more difficult to discriminate than a non-identical pair in the decision of whether the shapes of a given pair are rotated-to-be-identical (Idr). The purpose of the present experiment is to examine whether the sameness of line lengths between two figures in a pair causes the discrimination of the pair to be as difficult as that of an Ax pair. Mutually isomorphic figures share common structural properties despite differences in shape. Ax pairs and Idr pairs are special cases of isomorphic pairs. Furthermore, an Ax pair and Idr pair share most of the superficial feature values, except the relative direction from one location to another location across an axis of symmetry is opposite for an Ax pair. Three types of mutually isomorphic (6, 4) figure pairs were generated: Idr; Ax; and non-identical, non-axisymmetric, isomorphic (Nd) pairs. Nd pairs were further classified into three subcategories according to the superficial feature values of the degree of line length differences.

This protocol describes a method for an experiment that examines whether specific graph and non-graph properties (features) are relevant to the recognition of figures. The method uses a database that stores various feature values of respective figures called (6 point, n line) figures.

This protocol introduces a method for generating strictly controlled and objectively defined stimuli for figure recognition experiments. A (6, n) figure ...

Design and Use of an Apparatus for Presenting Graspable Objects in 3D Workspace

Reaching and grasping are highly-coupled movements, and their underlying neural dynamics have been widely studied in the last decade. To distinguish reaching and grasping encodings, it is essential to present different object identities independent of their positions. Presented here is the design of an automatic apparatus that is assembled with a turning table and three-dimensional (3D) translational device to achieve this goal. The turning table switches different objects corresponding to different grip types while the 3D translational device transports the turning table in 3D space. Both are driven independently by motors so that the target position and object are combined arbitrarily. Meanwhile, wrist trajectory and grip types are recorded via the motion capture system and touch sensors, respectively. Furthermore, representative results that demonstrate successfully trained monkey using this system are described. It is expected that this apparatus will facilitate researchers to study kinematics, neural principles, and brain-machine interfaces related to upper limb function.

Presented here is a protocol to build an automatic apparatus that guides a monkey to perform the flexible reach-to-grasp task. The apparatus combines a 3D translational device and turning table to present multiple objects in an arbitrary position in 3D space.

Reaching and grasping are highly-coupled movements, and their underlying neural dynamics have been widely studied in the last decade. To distinguish ...