Hard Discrimination Research Articles

SpatialSim: Recognizing Spatial Configurations of Objects With Graph Neural Networks.

An embodied, autonomous agent able to set its own goals has to possess geometrical reasoning abilities for judging whether its goals have been achieved, namely it should be able to identify and discriminate classes of configurations of objects, irrespective of its point of view on the scene. However, this problem has received little attention so far in the deep learning literature. In this paper we make two key contributions. First, we propose SpatialSim (Spatial Similarity), a novel geometrical reasoning diagnostic dataset, and argue that progress on this benchmark would allow for diagnosing more principled approaches to this problem. This benchmark is composed of two tasks: “Identification” and “Discrimination,” each one instantiated in increasing levels of difficulty. Secondly, we validate that relational inductive biases—exhibited by fully-connected message-passing Graph Neural Networks (MPGNNs)—are instrumental to solve those tasks, and show their advantages over less relational baselines such as Deep Sets and unstructured models such as Multi-Layer Perceptrons. We additionally showcase the failure of high-capacity CNNs on the hard Discrimination task. Finally, we highlight the current limits of GNNs in both tasks.

The effects of discrimination on the adoption of different strategies in selective stopping

Selective stopping is demanded in situations where responses must be suppressed to certain signals, but not others. To explore this type of inhibition, the standard stop-signal task has been modified to include a selective implementation of response inhibition by introducing a new stimulus that participants should ignore. However, a stimulus-selective stop-signal task can be performed following different strategies. Some participants fulfill the selective implementation of the stopping process after discriminating the stop and ignore signals, but some others stop the ongoing response whenever any new stimulus appears. The factors that influence this strategy choice are being explored, where both task and participant variables are under consideration. This study aimed to investigate whether the difficulty in discriminating between stop and ignore signals influences strategy adoption. Additionally, we examined whether participants modify their strategy in a flexible manner throughout the task in alternating easy and hard discrimination condition blocks. In the easy discrimination condition, the stop and the ignore signals differed both in color and shape, whereas in the hard discrimination condition, they only differed in shape. Our results from 64 participants revealed that manipulating the difficulty of signal discrimination strongly influenced strategy choice. Also, we found that participants can adapt their strategy according to task demands. They preferentially adopted a selective stopping strategy when discrimination was easy, whereas they changed to a nonselective stopping strategy under the hard discrimination condition. Overall, results from the current study suggest that signal discrimination difficulty influences the adoption of strategies in selective stopping.

Hard and soft age discrimination: the dual nature of workplace discrimination

The paper concentrates on the problem of age discrimination in the labour market and the way it can be conceptualised and measured in a multi-disciplinary way. The approach proposed here combines two understandings of age discrimination-a sociological and legal one, what allows for a fuller and expanded understanding of ageism in the workplace. At the heart of the study is a survey carried out in Poland with a sample of 1000 men and women aged 45-65years. The study takes a deeper and innovative look into the issue of age discrimination in employment. Confirmatory factor analysis with WLSMV estimation and logistic regressions were used to test the hypotheses. The study shows that age discrimination in labour market can take on different forms: hard and soft, where the hard type of age discrimination mirrors the legally prohibited types of behaviours and those which relate to the actual decisions of employers which can impact on the employee's career development. The soft discrimination corresponds with those occurrences, which are not inscribed in the legal system per se, are occurring predominantly in the interpersonal sphere, but can nevertheless have negative consequences. Soft discrimination was experienced more often (28.6% of respondents) than hard discrimination (15.7%) with higher occurrences among women, persons in precarious job situation or residents of urban areas. The role of education was not confirmed to influence the levels of perceived age discrimination.

Neural cascade of conflict processing: Not just time-on-task

In visual conflict tasks (e.g., Stroop or flanker), response times (RTs) are generally longer on incongruent trials relative to congruent ones. Two event-related-potential (ERP) components classically associated with the processing of stimulus conflict are the fronto-central, incongruency-related negativity (Ninc) and the posterior late-positive complex (LPC), which are derived from the ERP difference waves for incongruent minus congruent trials. It has been questioned, however, whether these effects, or other neural measures of incongruency (e.g., fMRI responses in the anterior cingulate), reflect true conflict processing, or whether such effects derive mainly from differential time-on-task. To address this question, we leveraged high-temporal-resolution ERP measures of brain activity during two behavioral tasks. The first task, a modified Erikson flanker paradigm (with congruent and incongruent trials), was used to evoke the classic RT and ERP effects associated with conflict. The second was a non-conflict control task in which, participants visually discriminated a single stimulus (with easy and hard discrimination conditions). Behaviorally, the parameters were titrated to yield similar RT effects of conflict and difficulty (27ms). Neurally, both within-task contrasts showed an initial fronto-central negative-polarity wave (N2-latency effect), but they then diverged. In the difficulty difference wave, the initial negativity led directly into the posterior LPC, whereas in the incongruency contrast the initial negativity was followed a by a second fronto-central negative peak (Ninc), which was then followed by a considerably longer-latency LPC. These results provide clear evidence that the longer processing for incongruent stimulus inputs do not just reflect time-on-task or difficulty, but include a true conflict-processing component.

An easy-to-hard effect after nonreinforced preexposure in a sweetness discrimination.

Experiments 1A and 1B used a taste-aversion procedure with rats to demonstrate that exposure to easily discriminated flavors along a dimension (1 % and 10 % sucrose) can facilitate learning a subsequent hard discrimination (4 % and 7 % sucrose) when one of those flavors is paired with illness. Experiment 1A compared the effects of preexposure to the easily discriminated flavors against exposure to the same stimuli used in the discrimination training or no exposure at all. Experiment 1B replicated the conditions in Experiment 1A, with 2 additional days of training and unrestricted access to the flavors on CS+/CS- trials in discrimination training. Contrary to findings with multidimensional stimuli (Scahill & Mackintosh, Journal of Experimental Psychology: Animal Behavior Processes, 30, 96-103, 2004; Suret & McLaren, The Quarterly Journal of Experimental Psychology, 56B, 30-42, 2003), we found that preexposure to the easily discriminable stimuli varying along a single dimension of sweetness facilitated subsequent discrimination training over the other conditions in each experiment. We discuss the results in terms of the ideas presented by Gibson (1969) and Mackintosh (Psychological Review, 82, 276-298, 1975) and in terms of hedonic variables not considered by theories of perceptual learning.

The easy-to-hard effect in a voluntary exposure to toxin paradigm with rats

In Experiment 1, one group of rats (Group Easy) received initial discrimination training consisting of alternate presentations of two flavor stimuli easily discriminable (presentations of a compound consisting of 0.15% saccharin and 0.15M lithium chloride, LiCl, and presentations of the saccharin alone). In a subsequent phase, these rats learned a hard version of the discrimination (in which the concentration of the saccharin solution was increased to 1.2%) faster than another group of rats (Group Hard) that received continuous training with the hard discrimination throughout all of the experiment. Experiment 2 led us to discard a possible interpretation of these results in terms of differences in the rates with which the neophobic reaction to the saccharin was habituated in the two groups. This study constitutes the first demonstration of an easy-hard effect in a free-intake toxin paradigm.

Poster #135 NEUROLOGICAL SOFT SIGNS AND PREPULSE INHIBITION OF THE STARTLE REFLEX IN PSYCHOSIS: A PILOT STUDY

P3a and P3b event-related brain potentials (ERPs) were elicited with an auditory 3-stimulus (target, distracter, standard) paradigm in which subjects responded only to the target.Distracter stimuli consisted of white noise, novel sounds, or a high frequency tone, with stimulus characteristics perceptually controlled. Task difficulty was varied as easy and hard by changing the pitch difference between the target and standard stimuli.Error rate was greater and response time longer for the hard task. P3a distracter amplitude was largest for the white noise and novel stimuli, with maximum amplitude over the central recording sites, and larger for the hard discrimination task. P3b target amplitude was unaffected by distracter type, maximum over the parietal recording sites, and smaller and later for the hard task.The findings indicate that white noise stimuli can produce reliable P3a components.White noise can be useful for clinical P3a applications, as it removes the variability of stimulus novelty.

Auditory discrimination learning and knowledge transfer in mice depends on task difficulty

Mice reproduce interesting effects in auditory discrimination learning and knowledge transfer discussed in human studies: (i) the advantage in the transfer from a hard to an easy task by benefits from transfer of procedural knowledge and information-integration learning, and (ii) the disadvantage in the transfer from easy to hard tasks by inability to generalize across perceptually different classes of stimuli together with initially unsuccessful attempts to transfer cognitive skills from one task to the other. House mice (NMRI strain) were trained in a shuttle-box stimulus discrimination task. They had to discriminate either between two pure tones of different frequencies (PT) or between two different modulation frequencies of an amplitude-modulated tone (AM). Then transfer of knowledge between these two tasks was tested. Mice rapidly learned PT discrimination within two to three training sessions (easy task). AM discrimination learning took longer and did not reach the high performance level of PT discrimination (hard task). No knowledge transfer was detected in animals first trained with the easy (PT) followed by the hard (AM) discrimination task. Mice benefited, however, from knowledge transfer when the AM discrimination was followed by the PT discrimination. When the task changed, confusion of conditioned stimuli occurred if the carrier frequency of the AM was the same as one of the frequencies in the PT task. These results show a hard-to-easy effect when possible knowledge transfer is tested between qualitatively different stimulus classes. The data establish mice as promising animal model for research on genetics of auditory perception and learning.

Causes of Wrongful Conviction: Looking at Student Knowledge

The current study investigates the impact of a criminal justice education on student knowledge about wrongful conviction. Past research has found fallibility of hard evidence (e.g., eyewitness misidentification), police and lawyer behaviors (e.g., tunnel vision), and social group discrimination to be underlying causes of wrongful conviction. We developed a survey to investigate student knowledge of these underlying causes, comparing participants in different years and programs of study. The findings suggest that criminal justice majors were at times more aware of the underlying causes of wrongful conviction than noncriminal justice majors, specifically in regards to the fallibility of hard evidence and social group discrimination. Criminal justice majors were not more knowledgeable in the areas of police and lawyer behavior. The implications of these findings are discussed in terms of the scope of criminal justice education and future careers in criminal justice.

P3a from auditory white noise stimuli

Objective P3a and P3b event-related brain potentials (ERPs) were elicited with an auditory 3-stimulus (target, distracter, standard) paradigm in which subjects responded only to the target. Methods Distracter stimuli consisted of white noise, novel sounds, or a high frequency tone, with stimulus characteristics perceptually controlled. Task difficulty was varied as easy and hard by changing the pitch difference between the target and standard stimuli. Results Error rate was greater and response time longer for the hard task. P3a distracter amplitude was largest for the white noise and novel stimuli, with maximum amplitude over the central recording sites, and larger for the hard discrimination task. P3b target amplitude was unaffected by distracter type, maximum over the parietal recording sites, and smaller and later for the hard task. Conclusions The findings indicate that white noise stimuli can produce reliable P3a components. Significance White noise can be useful for clinical P3a applications, as it removes the variability of stimulus novelty.

The Easy to Hard Effect and Perceptual Learning in Flavor Aversion Conditioning.

In experiments on the easy to hard effect, pretraining on an easy discrimination results in better performance on a harder version of the discrimination than pretraining on the hard discrimination itself. In addition, some theories posit that unreinforccd preexposure to the easy discrimination should be as effective as differentially reinforced easy pretraining in producing the easy to hard effect. Two experiments on flavor aversion conditioning in rats demonstrated the basic easy to hard effect. However, in neither experiment was easy preexposure more effective than hard preexposure in enhancing learning of the hard discrimination. Indeed, in Experiment 2, rats preexposed to an easy discrimination learned the hard discrimination significantly more slowly than those preexposed to the hard discrimination itself.

Extradimensional transfer in the easy-to-hard effect

In three experiments analyzing determinants of the easy-to-hard effect, pigeons acquired a hard discrimination after training on other problems. Intradimensional pretraining resulted in immediate transfer to the hard discrimination. Extradimensional pretraining consistently did not produce immediate transfer but did facilitate learning rate. In Experiment 1, the compounding of cues from an easy extradimentsional discrimination with those from the hard discrimination resulted in the former overshadowing the latter. When different types of extradimensional discriminations were introduced in Experiments 2 and 3, the degree of transfer was not proportional to the similarity in incidental background cues across problems. The findings indicate that in the easy-to-hard effect: (a) intra- and extradimensional mechanisms jointly contribute to the development of stimulus control, (b) intradimensional transfer is more consistent with the gradient-interaction model than the selective attention model, and (c) extradimensional transfer is better accounted for by the construct of general attentiveness rather than by the neutralization of background cues.

The easy-to-hard effect: Transfer along the dimension of orientation in the rat

Long-Evans rats were trained on an easy simultaneous discrimination problem and then transferred to a hard discrimination problem. The discriminanda were different orientations of stripes. In Experiment I, transfer was intradimensional with stimulus generalization controlled. The easy-to-hard effect was not found. In Experiment II transfer was intradimensional and either compatible (nonreversal) or incompatible (reversal). With compatible transfer, rats trained on a prior easy problem learned the hard problem faster than rats trained only on the hard problem. Persistent negative transfer was found with incompatible transfer. Attention was not supported as underlying the easy-to-hard effect. Explanations based on specific sources of intradimensional transfer, such as stimulus generalization or adaptation level, are suggested.

CHILDREN'S SELECTIVE ATTENTION TO STIMULI: STAGE OR SET?

GAINES, ROSSLYN. Children's Selective Attention to Stimuli: Stage or Set? CHILD DEVELOPMENT, 1970, 41, 979-991. The reliability of young children's selective attention to color and form dimensions was measured among two S types:-color and form selector Ss were assigned either to experimental training (on a dimension different than their dominant selection), to same training on their dominant choice dimension, or a no-training control group. Trained Ss had either hard or easy discrimination training over a 5-week period. The results indicate significant changes in selective attention among both color and form selectors given hard training and among color selectors given easy training. Form selectors given easy training showed change trends in the appropriate direction. Control color and form Ss show no significant changes in selection. The results show selective attention to color or form can be experimentally changed and is not developmentally determined for all Ss. Other sources of attention to color and form dimensions are discussed.

A Comparison of Two Discrimination Procedures in Avoidance Conditioning in the White Rat.

It is theoretically inferred that the discrimination in avoidance conditioning is difficult in typical discrimination procedure when two stimuli to be discriminated are very similar. PAVLOV and LAWRENCE have reported that a difficult discrimination between two quite similar stimuli is more efficient when subjects are first trained on an easy discrimination between two dissimilar stimuli and then gradually approach the difficult one than if all the training is given directly on the difficult discrimination. The purpose of this experiment is to compare the efficiency of these two procedures on discrimination in avoidance conditioning.Method Subjects : The Ss were 49 male albino rats. Apparatus : The apparatus was the modified MOWRER-MILLER shuttlebox. Procedure : After the establishment of avoidance conditioning to the CS which was 2000 cps tone, dicrimination training started. Hard Discrimination Group-I (HDG-I) was trained on the discrimination between 2000 cps (S+) and 1500 cps tone (S-) throughout 15 days. Hard Discrimination Group-II (HDG-II) was given the same procedure as HDG-I, but training was continued for 25 days. Gradual Transition Group-I (GTG-I) started on the discrimination between 2000 cps and 500 cps tone (S-) and then the S- gradually approached the 1500 cps tone through a series of graduated steps. The S- rose to 1500 cps by giving 250 cps every three days. Gradual Transition Group-II (GTG-II) was giving the same procedure as GTG-I, but the S- rose every five days (See Table 1).Results 1). The discrimination curves for each group are shown in Fig. 1 and 2. There was statistically significant difference between the number of responses to the S+ and S- at the last step of discrimination training for each group. This means that discrimination between S+and S- was established for each group. 2). In order to make comparisons between groups, discrimination ratios (S+-S-/S+) were calculated as an indicator of discrimination learning. Curves of them in the last training step for four groups are presented in Fig. 3. As a result of statistical comparisons between groups on these ratios, no significant difference was shown between HDG-I and GTG-I, but between HDG-II and GTG-II. This suggests that the difficult discrimination between two very similar stimuli in avoidance conditioning was more efficient when subjects approached the difficult discrimination through a series of graduated steps than if all the training was given directly on the difficult one. This also suggests that one of the important factors for this effect was the duration of a step, that is to say, this effect was not obtained in case of the short duration of a step.