Effects of Pattern Orientation and Number of Symmetry Axes on the Detection of Mirror Symmetry in Dot and Solid Patterns

Perception ◽  
1998 ◽  
Vol 27 (8) ◽  
pp. 965-976 ◽  
Author(s):  
Peter Wenderoth ◽  
Sebastian Welsh
Keyword(s):  
Reaction Time ◽  
Mirror Symmetry ◽  
Superior Performance ◽  
Pattern Goodness ◽  
Axes Of Symmetry ◽  
Percentage Correct

It has been postulated that as the number of axes of symmetry in a pattern increases, so pattern ‘goodness’ increases. Recently, a distinction was made between two different theoretical accounts of regularity or ‘goodness’ in relation to patterns with mirror symmetry: the ‘transformational’ and the ‘holographic’ models. It was argued that the former predicts a ‘goodness’ ordering of four > three > two > one whereas the latter predicts four > two > three > one, where ‘>’ means greater regularity or goodness. In three experiments, we have tested these predictions. In experiment 1, we measured percentage correct and reaction time to dot patterns which had one, two, three, or four axes of symmetry and were flashed for 150 ms. Experiment 2 was identical except that patterns were presented for 2000 ms. In experiment 3, dot patterns were replaced by solid shapes which also had one, two, three, or four axes of symmetry. Although it was found that stimuli with four axes clearly allowed superior performance to that of stimuli with one axis, results obtained with stimuli with two and three axes were almost identical and in between those obtained with one and four axes. The data thus support the suggestion that extra axes add ‘goodness’ to symmetrical patterns but not in a monotonic fashion.

scholarly journals Adaptive aspects of impulsivity and interactions with effects of catecholaminergic agents in the 5-choice serial reaction time task: implications for ADHD

2021 ◽  
Author(s):  
Chiara Toschi ◽  
Mona El-Sayed Hervig ◽  
Parisa Moazen ◽  
Maximilian G. Parker ◽  
Jeffrey W. Dalley ◽  
...  
Keyword(s):  
Reaction Time ◽  
Reaction Time Task ◽  
Serial Reaction Time Task ◽  
Superior Performance ◽  
Serial Reaction Time ◽  
Impaired Performance ◽  
Time Task ◽  
Serial Reaction ◽  
Behavioural Profile ◽  
Improved Performance

Abstract Background Work in humans has shown that impulsivity can be advantageous in certain settings. However, evidence for so-called functional impulsivity is lacking in experimental animals. Aims This study investigated the contexts in which high impulsive (HI) rats show an advantage in performance compared with mid- (MI) and low impulsive (LI) rats. We also assessed the effects of dopaminergic and noradrenergic agents to investigate underlying neurotransmitter mechanisms. Methods We tested rats on a variable inter-trial interval (ITI) version of the 5-choice serial reaction time task (5CSRTT). Rats received systemic injections of methylphenidate (MPH, 1 mg/kg and 3 mg/kg), atomoxetine (ATO, 0.3 mg/kg and 1 mg/kg), amphetamine (AMPH, 0.2 mg/kg), the alpha-2a adrenoceptor antagonist atipamezole (ATI, 0.3 mg/kg) and the alpha-1 adrenoceptor agonist phenylephrine (PHEN, 1 mg/kg) prior to behavioural testing. Results Unlike LI rats, HI rats exhibited superior performance, earning more reinforcers, on short ITI trials, when the task required rapid responding. MPH, AMPH and ATI improved performance on short ITI trials and increased impulsivity in long ITI trials, recapitulating the behavioural profile of HI. In contrast, ATO and PHEN impaired performance on short ITI trials and decreased impulsivity, thus mimicking the behavioural profile of LI rats. The effects of ATO were greater on MI rats and LI rats. Conclusions These findings indicate that impulsivity can be advantageous when rapid focusing and actions are required, an effect that may depend on increased dopamine neurotransmission. Conversely, activation of the noradrenergic system, with ATO and PHEN, led to a general inhibition of responding.

scholarly journals Goodness of Regularity in Dot Patterns: Global Symmetry, Local Symmetry, and Their Interactions

Perception ◽  
10.1068/p5794 ◽  
2007 ◽  
Vol 36 (9) ◽  
pp. 1305-1319 ◽  
Author(s):  
Massimo Nucci ◽  
Johan Wagemans
Keyword(s):  
Mirror Symmetry ◽  
Local Symmetry ◽  
Detection Task ◽  
Global Symmetry ◽  
Different Types ◽  
Operational Models ◽  
Local Mirror Symmetry ◽  
Axes Of Symmetry ◽  
Global And Local ◽  
Short Presentation

Goodness is a classic Gestalt notion defined as salience or perceptual strength of a given pattern. All operational models of goodness have assigned a central role to mirror symmetry but not much attention has been paid to the distinction between global and local mirror symmetry, and their possible interactions. We designed eight different types of dot patterns (all consisting of 80 dots), combining different numbers (0, 1, and 2) and relative orientations (parallel or orthogonal to each other) of local and global axes of symmetry (affecting 50% or 100% of the dots, respectively) at different absolute orientations (vertical and horizontal). Each of 640 trials consisted of a short presentation of a new dot pattern, which subjects had to classify as regular or random. We hypothesised that the overall goodness of patterns is not the simple sum of the amount of regularity present in them but depends on the cooperation and competition between symmetries. The results confirmed our hypothesis, showing that performance in this regularity-detection task did not increase in a linear way when some symmetries were added to other symmetries.

Response Time and Percentage Correct as Measures of Hearing Aid Performance

1983 ◽  
Vol 48 (4) ◽  
pp. 409-414
Author(s):  
John M. Seavertson ◽  
Roderick O. McLennan
Keyword(s):  
Response Time ◽  
Frequency Response ◽  
Hearing Aids ◽  
High Frequency ◽  
Superior Performance ◽  
Time Data ◽  
High Frequency Response ◽  
Discriminating Power ◽  
Correct Data ◽  
Percentage Correct

A paradigm yielding response time and percentage correct data was implemented to assess the relative efficacy in differentiating subjects' performance between two disparate hearing aids. These aids represented high-frequency response (HFR) and conventional-frequency response (CFR) categories. Ten men with flat, moderate, sensorineural hearing losses were employed as subjects. The results revealed that (a) percentage correct measures did not differentiate between the two experimental aids, (b) response time measures did discriminate between the aids, and (c) response time data revealed superior performance with the CFR compared to the HFR instrument. Implementation of this method is advocated to increase the discriminating power of word recognition testing.

Eye Movements in Judgements of Facial Expressions

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 297-297
Author(s):  
Y Osada ◽  
Y Nagasaka ◽  
R Yamazaki
Keyword(s):  
Eye Movements ◽  
Reaction Time ◽  
Facial Expressions ◽  
Corneal Reflection ◽  
Emotional Faces ◽  
The Face ◽  
Facial Expressions Of Emotion ◽  
Percentage Correct

We recorded eye movements by the method of corneal reflection while ten subjects viewed schematic faces drawn by lines. Each subject viewed different emotional faces: happy, angry, sad, disgusted, interested, frightened, and surprised. We measured the subject's judgements in terms of percentage ‘correct’ and reaction time. Schematic faces were composed of the face outline contours and of the brow, eyes, nose, and mouth which could all be modified to produce particular expressions. By masking parts of the face, we examined which features would have the greatest effects on judgements of emotion. Subjects always gave a saccade to the eyes and fixated even when the eyes were not important for the judgement. They also gave a saccade to the centre of the face and fixated it even when only the mouth was presented. The presentation of only the brow decreased the correct rate on the expression of ‘surprise’ but played an important role in the ‘sad’ judgement. The ‘angry’ judgement depended significantly on the brow and mouth. The eyes contributed greatly to the ‘disgusted’ judgement. These results suggest that the judgement of facial expressions of emotion can be strongly affected by each part of the schematic face. The concentration of saccades on the centre of the face suggests that the ‘configuration balance’ of the face is also likely to be important.

scholarly journals Auditory cognition and perception of action video game players

2019 ◽  
Author(s):  
Hannah J Stewart ◽  
Jasmin L Martinez ◽  
Audrey Perdew ◽  
C. Shawn Green ◽  
David R Moore
Keyword(s):  
Reaction Time ◽  
Video Game ◽  
Visual Learning ◽  
Reaction Time Task ◽  
Superior Performance ◽  
Probabilistic Thinking ◽  
Action Video Game ◽  
Auditory Cognition ◽  
Game Players ◽  
Auditory Tasks

A training method to improve speech hearing in noise has proven elusive, with most methods failing to transfer to untrained tasks. In contrast, transfer of visual learning to untrained tasks has been found in action video game players (AVGPs). It has been proposed that AVGP training improves underlying probabilistic thinking. However, most evidence is based on untrained visual tasks. This study aimed to expand the investigation to untrained auditory tasks to test cross-modal generalization, a tenet of learned probabilistic thinking. Eighty participants with mixed AVGP experience were tested on a visual reaction time task that has reliably shown superior performance in AVGPs compared to non-players and multi-genre video game players. Auditory cognition and perception were tested using auditory reaction time and two speech-in-noise tasks. Performance of AVGPs on the visual task replicated previous positive findings. However, no significant benefit of training was found on the auditory tasks. We suggest that, while AVGPs interact meaningfully with a rich visual environment during play, they may not interact with the games’ auditory environment. These results suggest that far transfer learning during action video game play is modality-specific and that an acoustically relevant auditory environment may be needed to improve auditory probabilistic thinking.

Mirror Symmetry Opposes Splitting of Chromatically Homogeneous Surfaces

Perception ◽  
10.1068/p3218 ◽  
2002 ◽  
Vol 31 (6) ◽  
pp. 693-709 ◽  
Author(s):  
Giulia Parovel ◽  
Stefano Vezzani
Keyword(s):  
Global Solution ◽  
Mirror Symmetry ◽  
Minimum Principle ◽  
Main Hypothesis ◽  
General Correlation ◽  
Local Factors ◽  
Single Figure ◽  
Axes Of Symmetry ◽  
Global And Local

Chromatically homogeneous surfaces can be seen as single figures but also as two or more overlapping figures. Local factors such as relatability have been proposed in order to explain perception of two or more figures (Kellman and Shipley, 1991 Cognitive Psychology23 141 – 221). However, even when these factors are at work, there are conditions favouring the perception of a single figure, which have not been explored so far. Here we propose that one such factor is the mirror symmetry of the surface. Three experiments were designed to test: (a) the main hypothesis, that mirror symmetry enhances perception of a single figure; (b) the role of orientation; (c) the effect of the number of axes of symmetry. The results show that (i) there is a good general correlation between mirror symmetry and perception of a single figure; (ii) vertical and horizontal axes of symmetry are the most effective; and (iii) the more axes of symmetry a surface has, the more likely is the perception of a single figure. These results suggest that mirror symmetry is an important factor in the perception of chromatically homogeneous displays. Some explanations are discussed, particularly one based on the rejection-of-coincidence principle [Rock, 1983 The Logic of Perception (Cambridge, MA: MIT Press)], and a version of the minimum principle in which the strength of the global solution depends on symmetry, whereas the strength of the splitting solution depends on the strength of local factors. In brief, global and local factors compete in determining the perceptual outcome in chromatically homogeneous surfaces.

Polygonal profiles of ferritin molecules

1983 ◽  
Vol 41 ◽  
pp. 600-601
Author(s):  
William H. Massover
Keyword(s):  
Axial Ratio ◽  
X Ray Diffraction ◽  
Rhombic Dodecahedron ◽  
Apparent Contradiction ◽  
Iron Storage ◽  
X Ray ◽  
Hexagonal Shape ◽  
Axes Of Symmetry ◽  
Apparent Conflict ◽  
Iron Storage Protein

The molecular structure of the iron-storage protein, ferritin, is becoming known in ever finer detail. The 24 apoferritin subunits (MW ca. 20,000) have a 2:1 axial ratio and are polymerized with 4:3:2 symmetry to form an outer shell surrounding a variable amount of microcrystalline iron, Recent x-ray diffraction results indicate that the projected outline of the native molecule has a quasi-hexagonal shape when viewed down the 3-fold axes of symmetry, and a quasi-square shape when looking down the 4-fold axes. To date, no electron microscope study has reported observing anything other than circular profiles, which would indicate that ferritin is strictly spherical. The apparent conflict between the "hollow sphere" of electron microscopy (E.M.) and the "truncated rhombic dodecahedron" of x-ray diffraction could reflect the poorer effective resolution of E.M. coming from radiation damage, staining, drying, etc. The present study investigates the detailed shape of individual ferritin molecules in order to search for the predicted aspherical profiles and to interpret the nature of this apparent contradiction.

In situ TEM Studies of agglomeration of sub-nanometer Ru layers in Ru/C multilayers

1992 ◽  
Vol 50 (1) ◽  
pp. 256-257
Author(s):  
Tai D. Nguyen ◽  
Ronald Gronsky ◽  
Jeffrey B. Kortright
Keyword(s):  
Layered Structure ◽  
Driving Force ◽  
High Energy ◽  
Superior Performance ◽  
In Situ Tem ◽  
Rayleigh Instability ◽  
Practical Applications ◽  
Transmission Electron ◽  
Diffraction Patterns

Nanometer period Ru/C multilayers are one of the prime candidates for normal incident reflecting mirrors at wavelengths < 10 nm. Superior performance, which requires uniform layers and smooth interfaces, and high stability of the layered structure under thermal loadings are some of the demands in practical applications. Previous studies however show that the Ru layers in the 2 nm period Ru/C multilayer agglomerate upon moderate annealing, and the layered structure is no longer retained. This agglomeration and crystallization of the Ru layers upon annealing to form almost spherical crystallites is a result of the reduction of surface or interfacial energy from die amorphous high energy non-equilibrium state of the as-prepared sample dirough diffusive arrangements of the atoms. Proposed models for mechanism of thin film agglomeration include one analogous to Rayleigh instability, and grain boundary grooving in polycrystalline films. These models however are not necessarily appropriate to explain for the agglomeration in the sub-nanometer amorphous Ru layers in Ru/C multilayers. The Ru-C phase diagram shows a wide miscible gap, which indicates the preference of phase separation between these two materials and provides an additional driving force for agglomeration. In this paper, we study the evolution of the microstructures and layered structure via in-situ Transmission Electron Microscopy (TEM), and attempt to determine the order of occurence of agglomeration and crystallization in the Ru layers by observing the diffraction patterns.

High Resolution Electron Microscopy of internal interfaces in layered materials

1990 ◽  
Vol 48 (4) ◽  
pp. 320-321
Author(s):  
Yoichi Ishida ◽  
Hideki Ichinose ◽  
Yutaka Takahashi ◽  
Jin-yeh Wang
Keyword(s):  
Grain Boundaries ◽  
Mirror Symmetry ◽  
Functional Materials ◽  
High Resolution Electron Microscopy ◽  
Layered Materials ◽  
Plane Boundary ◽  
Chemical Information ◽  
Layer Plane ◽  
High Tc ◽  
Cubic Metals

Layered materials draw attention in recent years in response to the world-wide drive to discover new functional materials. High-Tc superconducting oxide is one example. Internal interfaces in such layered materials differ significantly from those of cubic metals. They are often parallel to the layer of the neighboring crystals in sintered samples(layer plane boundary), while periodically ordered interfaces with the two neighboring crystals in mirror symmetry to each other are relatively rare. Consequently, the atomistic features of the interface differ significantly from those of cubic metals. In this paper grain boundaries in sintered high-Tc superconducting oxides, joined interfaces between engineering ceramics with metals, and polytype interfaces in vapor-deposited bicrystal are examined to collect atomic information of the interfaces in layered materials. The analysis proved that they are not neccessarily more complicated than that of simple grain boundaries in cubic metals. The interfaces are majorly layer plane type which is parallel to the compound layer. Secondly, chemical information is often available, which helps the interpretation of the interface atomic structure.

The limits of strain and lattice parameter measurements by CBED

1989 ◽  
Vol 47 ◽  
pp. 518-519
Author(s):  
Hamish L. Fraser
Keyword(s):  
Electron Beam ◽  
Mirror Symmetry ◽  
Local Symmetry ◽  
Lattice Parameter ◽  
Growth Direction ◽  
Surface Relaxation ◽  
Strained Layer ◽  
Axis Parallel ◽  
Local Lattice ◽  
Strained Layer Superlattice

The topic of strain and lattice parameter measurements using CBED is discussed by reference to several examples. In this paper, only one of these examples is referenced because of the limitation of length. In this technique, scattering in the higher order Laue zones is used to determine local lattice parameters. Work (e.g. 1) has concentrated on a model strained-layer superlattice, namely Si/Gex-Si1-x. In bulk samples, the strain is expected to be tetragonal in nature with the unique axis parallel to [100], the growth direction. When CBED patterns are recorded from the alloy epi-layers, the symmetries exhibited by the patterns are not tetragonal, but are in fact distorted from this to lower symmetries. The spatial variation of the distortion close to a strained-layer interface has been assessed. This is most readily noted by consideration of Fig. 1(a-c), which show enlargements of CBED patterns for various locations and compositions of Ge. Thus, Fig. 1(a) was obtained with the electron beam positioned in the center of a 5Ge epilayer and the distortion is consistent with an orthorhombic distortion. When the beam is situated at about 150 nm from the interface, the same part of the CBED pattern is shown in Fig. 1(b); clearly, the symmetry exhibited by the mirror planes in Fig. 1 is broken. Finally, when the electron beam is positioned in the center of a 10Ge epilayer, the CBED pattern yields the result shown in Fig. 1(c). In this case, the break in the mirror symmetry is independent of distance form the heterointerface, as might be expected from the increase in the mismatch between 5 and 10%Ge, i.e. 0.2 to 0.4%, respectively. From computer simulation, Fig.2, the apparent monocline distortion corresponding to the 5Ge epilayer is quantified as a100 = 0.5443 nm, a010 = 0.5429 nm and a001 = 0.5440 nm (all ± 0.0001 nm), and α = β = 90°, γ = 89.96 ± 0.02°. These local symmetry changes are most likely due to surface relaxation phenomena.

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