Christopher Madan | University of Nottingham (original) (raw)

Papers by Christopher Madan

Animal cognition, Jan 23, 2016

Encoding multiple cues can improve the accuracy and reliability of navigation and goal localizati... more Encoding multiple cues can improve the accuracy and reliability of navigation and goal localization. Problems may arise, however, if one cue is displaced and provides information which conflicts with other cues. Here we investigated how pigeons cope with cue conflict by training them to locate a goal relative to two landmarks and then varying the amount of conflict between the landmarks. When the amount of conflict was small, pigeons tended to integrate both cues in their search patterns. When the amount of conflict was large, however, pigeons used information from both cues independently. This context-dependent strategy for resolving spatial cue conflict agrees with Bayes optimal calculations for using information from multiple sources.

F1000Research, 2015

While magnetic resonance imaging (MRI) data is itself 3D, it is often difficult to adequately pre... more While magnetic resonance imaging (MRI) data is itself 3D, it is often difficult to adequately present the results papers and slides in 3D. As a result, findings of MRI studies are often presented in 2D instead. A solution is to create figures that include perspective and can convey 3D information; such figures can sometimes be produced by standard functional magnetic resonance imaging (fMRI) analysis packages and related specialty programs. However, many options cannot provide functionality such as visualizing activation clusters that are both cortical and subcortical (i.e., a 3D glass brain), the production of several statistical maps with an identical perspective in the 3D rendering, or animated renderings. Here I detail an approach for creating 3D visualizations of MRI data that satisfies all of these criteria. Though a 3D 'glass brain' rendering can sometimes be difficult to interpret, they are useful in showing a more overall representation of the results, whereas the traditional slices show a more local view. Combined, presenting both 2D and 3D representations of MR images can provide a more comprehensive view of the study's findings.

F1000Research, 2015

Independent of the actual results, some scientific articles are more memorable than others. As an... more Independent of the actual results, some scientific articles are more memorable than others. As anyone who has written an article collaboratively knows, there are numerous ways a manuscript can be written to convey the same general ideas. To aid with this, many scientific writing books and editorials provide advice, often anecdotal, on how to make articles more memorable. Here I ground these suggestions with empirical support from memory research. Specifically, I suggest that researchers consider how to emphasize their work's novelty, strive to describe their work using concrete, easy-to-understand terms, and use caution when attempting to evoke an emotional response in the reader. I also discuss considerations in title selections and conference presentations.

Journal of experimental psychology. General, 2015

People are often risk averse when making decisions under uncertainty. When those decisions are ba... more People are often risk averse when making decisions under uncertainty. When those decisions are based on past experience, people necessarily rely on their memories. Thus, what is remembered at the time of the choice should influence risky choice. We tested this hypothesis by priming memory for past outcomes in a simple risky-choice task. In the task, people repeatedly chose between a safe option and a risky option that paid off with a larger or smaller reward with a 50/50 chance. Some trials were preceded by a priming cue that was previously paired with one of the outcomes. We found that priming cues associated with wins caused people to become risk seeking, whereas priming cues associated with relative losses had little effect. These results suggest that people can be induced to be more risk seeking through subtle reminders of previous winning experiences.

F1000Research, 2014

When studying animal behaviour within an open environment, movement-related data are often import... more When studying animal behaviour within an open environment, movement-related data are often important for behavioural analyses. Therefore, simple and efficient techniques are needed to present and analyze the data of such movements. However, it is challenging to present both spatial and temporal information of movements within a two-dimensional image representation. To address this challenge, we developed the spectral time-lapse (STL) algorithm that re-codes an animal's position at every time point with a time-specific color, and overlays it with a reference frame of the video, to produce a summary image. We additionally incorporated automated motion tracking, such that the animal's position can be extracted and summary statistics such as path length and duration can be calculated, as well as instantaneous velocity and acceleration. Here we describe the STL algorithm and offer a freely available MATLAB toolbox that implements the algorithm and allows for a large degree of end-user control and flexibility.

Journal of Behavioral Decision Making, 2014

Whether buying stocks or playing the slots, people making real-world risky decisions often rely o... more Whether buying stocks or playing the slots, people making real-world risky decisions often rely on their experiences with the risks and rewards. These decisions, however, do not occur in isolation but are embedded in a rich context of other decisions, outcomes, and experiences. In this paper, we systematically evaluate how the local context of other rewarding outcomes alters risk preferences. Through a series of four experiments on decisions from experience, we provide evidence for an extreme-outcome rule, whereby people overweight the most extreme outcomes (highest and lowest) in a given context. As a result, people should be more risk seeking for gains than losses, even with equally likely outcomes. Across the experiments, the decision context was varied so that the same outcomes served as the high extreme, low extreme, or neither. As predicted, people were more risk seeking for relative gains, but only when the risky option potentially led to the high-extreme outcome. Similarly, people were more risk averse for relative losses, but only when the risky option potentially led to the low-extreme outcome. We conclude that in risky decisions from experience, the biggest wins and the biggest losses seem to matter more than they should. decision context, +40 and À40 were the two extremes.

Cognitive Processing, 2012

Traditionally, higher-level cognition has been described as including processes such as attention... more Traditionally, higher-level cognition has been described as including processes such as attention, memory, language, and decision-making. However, motor processing and motor imagery are important aspects of cognition that have typically been considered outside of the traditional view. Recent research has demonstrated that there may be a critical functional relationship between motor imagery and other higher-level cognitive processes. Here we present a review of the extant literature on motor imagery and cognition, as well as outline four hurdles that must be addressed before the field investigating the influence of motor-based processes on higher-level cognition can be moved forward. These hurdles include problems distinguishing between visual and motor processes, addressing the differences in tasks and stimuli used to evoke motor imagery, accounting for individual differences in motor imagery ability, and identifying the appropriate neural correlates. It is important that these hurdles are addressed in future research so we can sprint forward and further our knowledge about this interesting relationship.

Eureka, Mar 26, 2012

Most undergraduates know that the professors that teach their classes are often also researchers.... more Most undergraduates know that the professors that teach their classes are often also researchers. But what exactly do they research? More importantly, what is research? Most departments in the Faculty of Science have research courses, not just at the 400-level, but sometimes at the 200-and 300-levels as well. Now, you're probably wondering what do students do in these classes, in research, and how can you get involved? I'm glad you asked... week. You are also expected to meet with the professor regularly (especially if ...

Animal cognition, 2015

Glass patterns (GPs) are static stimuli that consist of randomly positioned dot-pairs that are sp... more Glass patterns (GPs) are static stimuli that consist of randomly positioned dot-pairs that are spatially integrated to create the perception of a global form. However, when multiple independently generated static GPs are presented sequentially (termed 'dynamic' GP), observers report a percept of coherent motion, and data show an improvement in sensitivity. This increased sensitivity has been attributed to a summation of the form signals provided by the individual GPs. In Experiment 1, we tested whether pigeons also show a heightened sensitivity to dynamic GPs. Our results show that pigeons are significantly better at learning to discriminate dynamic GPs from noise compared with static GPs. However, in contrast to previous research, we found that pigeons did not perform well enough with our static GPs to extract sensitivity measurements. In Experiment 2, we compared our static GPs to those that have been used previously. We show that the difference in the comparison noise pat...

Vision Research, 2015

The ability to perceive complex objects in the environment requires that the visual system integr... more The ability to perceive complex objects in the environment requires that the visual system integrate local form information into global shapes. Glass patterns (GPs) are stimuli that are commonly used to study this integration process. GPs consist of randomly positioned dot-pairs oriented in a coherent way to create a global form. When multiple GPs are presented sequentially, observers report a percept of illusory coherent motion and have lower detection thresholds relative to a single presentation GPs. The percept of illusory motion has been attributed to the visual system interpreting the dot-pairs in GPs as motion streaks. However, it remains unclear why dynamic GPs are detected at lower thresholds than static GPs. Two main differences exist between static and dynamic GPs: (a) dynamic GPs contain multiple presentations of global form signals compared to a single presentation in static GPs and (b) dynamic GPs have a greater temporal frequency than static GPs. Here we investigated which of these two factors contributed to the heightened sensitivities for dynamic GPs. We systematically varied the number of unique GPs and the rate at which each unique frame is presented (i.e., temporal frequency). The results show that, within the range of temporal frequency used, the primary influence on detection thresholds was the number of unique frames. These results suggest that the improved detection sensitivities can be driven by a mechanism of temporal summation of global form.

Animal cognition, 2014

Visiting multiple locations and returning to the start via the shortest route, referred to as the... more Visiting multiple locations and returning to the start via the shortest route, referred to as the traveling salesman (or salesperson) problem (TSP), is a valuable skill for both humans and non-humans. In the current study, pigeons were trained with increasing set sizes of up to six goals, with each set size presented in three distinct configurations, until consistency in route selection emerged. After training at each set size, the pigeons were tested with two novel configurations. All pigeons acquired routes that were significantly more efficient (i.e., shorter in length) than expected by chance selection of the goals. On average, the pigeons also selected routes that were more efficient than expected based on a local nearest-neighbor strategy and were as efficient as the average route generated by a crossing-avoidance strategy. Analysis of the routes taken indicated that they conformed to both a nearest-neighbor and a crossing-avoidance strategy significantly more often than expected by chance. Both the time taken to visit all goals and the actual distance traveled decreased from the first to the last trials of training in each set size. On the first trial with novel configurations, average efficiency was higher than chance, but was not higher than expected from a nearest-neighbor or crossing-avoidance strategy. These results indicate that pigeons can learn to select efficient routes on a TSP problem.

Acta psychologica, 2014

Imageability is known to enhance association-memory for verbal paired-associates. High-imageabili... more Imageability is known to enhance association-memory for verbal paired-associates. High-imageability words can be further subdivided by manipulability, the ease by which the named object can be functionally interacted with. Prior studies suggest that motor processing enhances item-memory, but impairs association-memory. However, these studies used action verbs and concrete nouns as the high-and low-manipulability words, respectively, confounding manipulability with word class. Recent findings demonstrated that nouns can serve as both highand low-manipulability words (e.g., CAMERA and TABLE, respectively), allowing us to avoid this confound. Here participants studied pairs of words that consisted of all possible pairings of high-and low-manipulability words and were tested with immediate cued recall. Recall was worse for pairs that contained high-manipulability words. In free recall, participants recalled more high-than low-manipulability words. Our results provide further evidence that manipulability influences memory, likely occurring through automatic motor imagery.

Experimental brain research, 2014

In the primate visual system, local motion signals are pooled to create a global motion percept. ... more In the primate visual system, local motion signals are pooled to create a global motion percept. Like primates, many birds are highly dependent on vision for their survival, yet relatively little is known about motion perception in birds. We used random-dot stimuli to investigate pigeons’ ability to detect complex motion (radial, rotation, and spiral) compared to humans. Our human participants had a significantly lower threshold for rotational and radial motion when compared to spiral motion. The data from the pigeons, however, showed that the pigeons were most sensitive to rotational motion and least sensitive to radial motion, while sensitivity for spiral motion was intermediate. We followed up the pigeon results with an investigation of the effect of display aperture shape for rotational motion and velocity gradient for radial motion. We found no effect of shape of the aperture on thresholds, but did observe that radial motion containing accelerating dots improved thresholds. However, this improvement did not reach the thresholds levels observed for rotational motion. In sum, our experiments demonstrate that the pooling mechanism in the pigeon motion system is most efficient for rotation.

Journal of sports sciences, 2014

Athletes have been shown to have greater movement imagery abilities than non-athletes. However, s... more Athletes have been shown to have greater movement imagery abilities than non-athletes. However, since these differences were observed using questionnaires where participants subjectively judged the vividness of performing imagined movements, it is possible that responses could be biased by other factors such as social desirability. One possible solution is to use an objective test, such as the Test of Ability in Movement Imagery (TAMI; Madan, C. R., & Singhal, A. (2013). Introducing TAMI: An objective test of ability in movement imagery. Journal of Motor Behavior, 45, 153–166.). Unfortunately, young adults perform relatively well on the TAMI, leaving little room for statistical sensitivity in observing higher scores. Here we propose an alternate scoring method for the TAMI that resolves this limitation by weighing items according to their difficulty. We apply this scoring method to existing data and show that this improves the TAMI’s selectivity to measuring ability in movement imagery, rather than related imagery processes. Thus, we have successfully improved the TAMI to be more suited for use with athletic populations.

Frontiers in systems neuroscience, 2014

FIGURE 1 | Graphical representation of the mathematical model developed by Berger et al. (2011) t... more FIGURE 1 | Graphical representation of the mathematical model developed by Berger et al. (2011) to simulate connectivity between CA3 and CA1 of the hippocampus. Figure adapted from Berger et al. (2013).

Frontiers in systems neuroscience, 2013

While the effects of reward, affect, and motivation on learning have each developed into their ow... more While the effects of reward, affect, and motivation on learning have each developed into their own fields of research, they largely have been investigated in isolation. As all three of these constructs are highly related, and use similar experimental procedures, an important advance in research would be to consider the interplay between these constructs. Here we first define each of the three constructs, and then discuss how they may influence each other within a common framework. Finally, we delineate several sources of evidence supporting the framework. By considering the constructs of reward, affect, and motivation within a single framework, we can develop a better understanding of the processes involved in learning and how they interplay, and work toward a comprehensive theory that encompasses reward, affect, and motivation.

Journal of motor behavior, 2013

Individual ability in mental imagery varies widely across individuals, leading to the development... more Individual ability in mental imagery varies widely across individuals, leading to the development of questionnaires to evaluate mental imagery. Within the domain of movement imagery, questionnaires have previously relied on subjective ratings of vividness, which may be influenced by additional factors such as motor skill confidence, success of imagined actions, and social desirability. These additional factors are of particular importance when making comparisons between samples from different populations, such as athletes versus nonathletes and patients versus healthy individuals. The authors present a novel test of ability in movement imagery (Test of Ability in Movement Imagery [TAMI]) that relies on objective measures and requires participants to make explicit imagined movements from an external perspective. In Study 1, the authors present evidence that young adults perform at a mid-level on the TAMI. In Study 2, they further compare performance on the TAMI with a battery of other measures to better characterize the TAMI by determining its similarities and differences with existing measures. The findings of both studies indicate the TAMI to be a valid and reliable measure of movement imagery ability. The authors additionally discuss future applications of the TAMI to athletic and clinical research.

Animal cognition, Jan 23, 2016

Encoding multiple cues can improve the accuracy and reliability of navigation and goal localizati... more Encoding multiple cues can improve the accuracy and reliability of navigation and goal localization. Problems may arise, however, if one cue is displaced and provides information which conflicts with other cues. Here we investigated how pigeons cope with cue conflict by training them to locate a goal relative to two landmarks and then varying the amount of conflict between the landmarks. When the amount of conflict was small, pigeons tended to integrate both cues in their search patterns. When the amount of conflict was large, however, pigeons used information from both cues independently. This context-dependent strategy for resolving spatial cue conflict agrees with Bayes optimal calculations for using information from multiple sources.

F1000Research, 2015

While magnetic resonance imaging (MRI) data is itself 3D, it is often difficult to adequately pre... more While magnetic resonance imaging (MRI) data is itself 3D, it is often difficult to adequately present the results papers and slides in 3D. As a result, findings of MRI studies are often presented in 2D instead. A solution is to create figures that include perspective and can convey 3D information; such figures can sometimes be produced by standard functional magnetic resonance imaging (fMRI) analysis packages and related specialty programs. However, many options cannot provide functionality such as visualizing activation clusters that are both cortical and subcortical (i.e., a 3D glass brain), the production of several statistical maps with an identical perspective in the 3D rendering, or animated renderings. Here I detail an approach for creating 3D visualizations of MRI data that satisfies all of these criteria. Though a 3D 'glass brain' rendering can sometimes be difficult to interpret, they are useful in showing a more overall representation of the results, whereas the traditional slices show a more local view. Combined, presenting both 2D and 3D representations of MR images can provide a more comprehensive view of the study's findings.

F1000Research, 2015

Independent of the actual results, some scientific articles are more memorable than others. As an... more Independent of the actual results, some scientific articles are more memorable than others. As anyone who has written an article collaboratively knows, there are numerous ways a manuscript can be written to convey the same general ideas. To aid with this, many scientific writing books and editorials provide advice, often anecdotal, on how to make articles more memorable. Here I ground these suggestions with empirical support from memory research. Specifically, I suggest that researchers consider how to emphasize their work's novelty, strive to describe their work using concrete, easy-to-understand terms, and use caution when attempting to evoke an emotional response in the reader. I also discuss considerations in title selections and conference presentations.

Journal of experimental psychology. General, 2015

People are often risk averse when making decisions under uncertainty. When those decisions are ba... more People are often risk averse when making decisions under uncertainty. When those decisions are based on past experience, people necessarily rely on their memories. Thus, what is remembered at the time of the choice should influence risky choice. We tested this hypothesis by priming memory for past outcomes in a simple risky-choice task. In the task, people repeatedly chose between a safe option and a risky option that paid off with a larger or smaller reward with a 50/50 chance. Some trials were preceded by a priming cue that was previously paired with one of the outcomes. We found that priming cues associated with wins caused people to become risk seeking, whereas priming cues associated with relative losses had little effect. These results suggest that people can be induced to be more risk seeking through subtle reminders of previous winning experiences.

F1000Research, 2014

When studying animal behaviour within an open environment, movement-related data are often import... more When studying animal behaviour within an open environment, movement-related data are often important for behavioural analyses. Therefore, simple and efficient techniques are needed to present and analyze the data of such movements. However, it is challenging to present both spatial and temporal information of movements within a two-dimensional image representation. To address this challenge, we developed the spectral time-lapse (STL) algorithm that re-codes an animal's position at every time point with a time-specific color, and overlays it with a reference frame of the video, to produce a summary image. We additionally incorporated automated motion tracking, such that the animal's position can be extracted and summary statistics such as path length and duration can be calculated, as well as instantaneous velocity and acceleration. Here we describe the STL algorithm and offer a freely available MATLAB toolbox that implements the algorithm and allows for a large degree of end-user control and flexibility.

Journal of Behavioral Decision Making, 2014

Whether buying stocks or playing the slots, people making real-world risky decisions often rely o... more Whether buying stocks or playing the slots, people making real-world risky decisions often rely on their experiences with the risks and rewards. These decisions, however, do not occur in isolation but are embedded in a rich context of other decisions, outcomes, and experiences. In this paper, we systematically evaluate how the local context of other rewarding outcomes alters risk preferences. Through a series of four experiments on decisions from experience, we provide evidence for an extreme-outcome rule, whereby people overweight the most extreme outcomes (highest and lowest) in a given context. As a result, people should be more risk seeking for gains than losses, even with equally likely outcomes. Across the experiments, the decision context was varied so that the same outcomes served as the high extreme, low extreme, or neither. As predicted, people were more risk seeking for relative gains, but only when the risky option potentially led to the high-extreme outcome. Similarly, people were more risk averse for relative losses, but only when the risky option potentially led to the low-extreme outcome. We conclude that in risky decisions from experience, the biggest wins and the biggest losses seem to matter more than they should. decision context, +40 and À40 were the two extremes.

Cognitive Processing, 2012

Traditionally, higher-level cognition has been described as including processes such as attention... more Traditionally, higher-level cognition has been described as including processes such as attention, memory, language, and decision-making. However, motor processing and motor imagery are important aspects of cognition that have typically been considered outside of the traditional view. Recent research has demonstrated that there may be a critical functional relationship between motor imagery and other higher-level cognitive processes. Here we present a review of the extant literature on motor imagery and cognition, as well as outline four hurdles that must be addressed before the field investigating the influence of motor-based processes on higher-level cognition can be moved forward. These hurdles include problems distinguishing between visual and motor processes, addressing the differences in tasks and stimuli used to evoke motor imagery, accounting for individual differences in motor imagery ability, and identifying the appropriate neural correlates. It is important that these hurdles are addressed in future research so we can sprint forward and further our knowledge about this interesting relationship.

Eureka, Mar 26, 2012

Most undergraduates know that the professors that teach their classes are often also researchers.... more Most undergraduates know that the professors that teach their classes are often also researchers. But what exactly do they research? More importantly, what is research? Most departments in the Faculty of Science have research courses, not just at the 400-level, but sometimes at the 200-and 300-levels as well. Now, you're probably wondering what do students do in these classes, in research, and how can you get involved? I'm glad you asked... week. You are also expected to meet with the professor regularly (especially if ...

Animal cognition, 2015

Glass patterns (GPs) are static stimuli that consist of randomly positioned dot-pairs that are sp... more Glass patterns (GPs) are static stimuli that consist of randomly positioned dot-pairs that are spatially integrated to create the perception of a global form. However, when multiple independently generated static GPs are presented sequentially (termed 'dynamic' GP), observers report a percept of coherent motion, and data show an improvement in sensitivity. This increased sensitivity has been attributed to a summation of the form signals provided by the individual GPs. In Experiment 1, we tested whether pigeons also show a heightened sensitivity to dynamic GPs. Our results show that pigeons are significantly better at learning to discriminate dynamic GPs from noise compared with static GPs. However, in contrast to previous research, we found that pigeons did not perform well enough with our static GPs to extract sensitivity measurements. In Experiment 2, we compared our static GPs to those that have been used previously. We show that the difference in the comparison noise pat...

Vision Research, 2015

The ability to perceive complex objects in the environment requires that the visual system integr... more The ability to perceive complex objects in the environment requires that the visual system integrate local form information into global shapes. Glass patterns (GPs) are stimuli that are commonly used to study this integration process. GPs consist of randomly positioned dot-pairs oriented in a coherent way to create a global form. When multiple GPs are presented sequentially, observers report a percept of illusory coherent motion and have lower detection thresholds relative to a single presentation GPs. The percept of illusory motion has been attributed to the visual system interpreting the dot-pairs in GPs as motion streaks. However, it remains unclear why dynamic GPs are detected at lower thresholds than static GPs. Two main differences exist between static and dynamic GPs: (a) dynamic GPs contain multiple presentations of global form signals compared to a single presentation in static GPs and (b) dynamic GPs have a greater temporal frequency than static GPs. Here we investigated which of these two factors contributed to the heightened sensitivities for dynamic GPs. We systematically varied the number of unique GPs and the rate at which each unique frame is presented (i.e., temporal frequency). The results show that, within the range of temporal frequency used, the primary influence on detection thresholds was the number of unique frames. These results suggest that the improved detection sensitivities can be driven by a mechanism of temporal summation of global form.

Animal cognition, 2014

Visiting multiple locations and returning to the start via the shortest route, referred to as the... more Visiting multiple locations and returning to the start via the shortest route, referred to as the traveling salesman (or salesperson) problem (TSP), is a valuable skill for both humans and non-humans. In the current study, pigeons were trained with increasing set sizes of up to six goals, with each set size presented in three distinct configurations, until consistency in route selection emerged. After training at each set size, the pigeons were tested with two novel configurations. All pigeons acquired routes that were significantly more efficient (i.e., shorter in length) than expected by chance selection of the goals. On average, the pigeons also selected routes that were more efficient than expected based on a local nearest-neighbor strategy and were as efficient as the average route generated by a crossing-avoidance strategy. Analysis of the routes taken indicated that they conformed to both a nearest-neighbor and a crossing-avoidance strategy significantly more often than expected by chance. Both the time taken to visit all goals and the actual distance traveled decreased from the first to the last trials of training in each set size. On the first trial with novel configurations, average efficiency was higher than chance, but was not higher than expected from a nearest-neighbor or crossing-avoidance strategy. These results indicate that pigeons can learn to select efficient routes on a TSP problem.

Acta psychologica, 2014

Imageability is known to enhance association-memory for verbal paired-associates. High-imageabili... more Imageability is known to enhance association-memory for verbal paired-associates. High-imageability words can be further subdivided by manipulability, the ease by which the named object can be functionally interacted with. Prior studies suggest that motor processing enhances item-memory, but impairs association-memory. However, these studies used action verbs and concrete nouns as the high-and low-manipulability words, respectively, confounding manipulability with word class. Recent findings demonstrated that nouns can serve as both highand low-manipulability words (e.g., CAMERA and TABLE, respectively), allowing us to avoid this confound. Here participants studied pairs of words that consisted of all possible pairings of high-and low-manipulability words and were tested with immediate cued recall. Recall was worse for pairs that contained high-manipulability words. In free recall, participants recalled more high-than low-manipulability words. Our results provide further evidence that manipulability influences memory, likely occurring through automatic motor imagery.

Experimental brain research, 2014

In the primate visual system, local motion signals are pooled to create a global motion percept. ... more In the primate visual system, local motion signals are pooled to create a global motion percept. Like primates, many birds are highly dependent on vision for their survival, yet relatively little is known about motion perception in birds. We used random-dot stimuli to investigate pigeons’ ability to detect complex motion (radial, rotation, and spiral) compared to humans. Our human participants had a significantly lower threshold for rotational and radial motion when compared to spiral motion. The data from the pigeons, however, showed that the pigeons were most sensitive to rotational motion and least sensitive to radial motion, while sensitivity for spiral motion was intermediate. We followed up the pigeon results with an investigation of the effect of display aperture shape for rotational motion and velocity gradient for radial motion. We found no effect of shape of the aperture on thresholds, but did observe that radial motion containing accelerating dots improved thresholds. However, this improvement did not reach the thresholds levels observed for rotational motion. In sum, our experiments demonstrate that the pooling mechanism in the pigeon motion system is most efficient for rotation.

Journal of sports sciences, 2014

Athletes have been shown to have greater movement imagery abilities than non-athletes. However, s... more Athletes have been shown to have greater movement imagery abilities than non-athletes. However, since these differences were observed using questionnaires where participants subjectively judged the vividness of performing imagined movements, it is possible that responses could be biased by other factors such as social desirability. One possible solution is to use an objective test, such as the Test of Ability in Movement Imagery (TAMI; Madan, C. R., & Singhal, A. (2013). Introducing TAMI: An objective test of ability in movement imagery. Journal of Motor Behavior, 45, 153–166.). Unfortunately, young adults perform relatively well on the TAMI, leaving little room for statistical sensitivity in observing higher scores. Here we propose an alternate scoring method for the TAMI that resolves this limitation by weighing items according to their difficulty. We apply this scoring method to existing data and show that this improves the TAMI’s selectivity to measuring ability in movement imagery, rather than related imagery processes. Thus, we have successfully improved the TAMI to be more suited for use with athletic populations.

Frontiers in systems neuroscience, 2014

FIGURE 1 | Graphical representation of the mathematical model developed by Berger et al. (2011) t... more FIGURE 1 | Graphical representation of the mathematical model developed by Berger et al. (2011) to simulate connectivity between CA3 and CA1 of the hippocampus. Figure adapted from Berger et al. (2013).

Frontiers in systems neuroscience, 2013

While the effects of reward, affect, and motivation on learning have each developed into their ow... more While the effects of reward, affect, and motivation on learning have each developed into their own fields of research, they largely have been investigated in isolation. As all three of these constructs are highly related, and use similar experimental procedures, an important advance in research would be to consider the interplay between these constructs. Here we first define each of the three constructs, and then discuss how they may influence each other within a common framework. Finally, we delineate several sources of evidence supporting the framework. By considering the constructs of reward, affect, and motivation within a single framework, we can develop a better understanding of the processes involved in learning and how they interplay, and work toward a comprehensive theory that encompasses reward, affect, and motivation.

Journal of motor behavior, 2013

Individual ability in mental imagery varies widely across individuals, leading to the development... more Individual ability in mental imagery varies widely across individuals, leading to the development of questionnaires to evaluate mental imagery. Within the domain of movement imagery, questionnaires have previously relied on subjective ratings of vividness, which may be influenced by additional factors such as motor skill confidence, success of imagined actions, and social desirability. These additional factors are of particular importance when making comparisons between samples from different populations, such as athletes versus nonathletes and patients versus healthy individuals. The authors present a novel test of ability in movement imagery (Test of Ability in Movement Imagery [TAMI]) that relies on objective measures and requires participants to make explicit imagined movements from an external perspective. In Study 1, the authors present evidence that young adults perform at a mid-level on the TAMI. In Study 2, they further compare performance on the TAMI with a battery of other measures to better characterize the TAMI by determining its similarities and differences with existing measures. The findings of both studies indicate the TAMI to be a valid and reliable measure of movement imagery ability. The authors additionally discuss future applications of the TAMI to athletic and clinical research.