Subjective perception of objects depends on the interaction between the validity of context-based expectations and signal reliability

Predictive coding theories of visual perception assume that expectations based on prior knowledge modulate the processing of information. However, the underlying mechanisms remain debated. Some accounts propose that expectations enhance the perception of expected relative to unexpected stimuli while others assume the opposite. Recently, the opposing process theory suggested that enhanced perception of expected vs. unexpected stimuli may occur alternatively depending upon the reliability of the visual signal. When the signal is noisy, perception would be biassed toward what is expected since anything else may be too noisy to be resolved. When the signal is unambiguous, perception would be biassed toward what diverges from expectations and is more informative. Our study tested this hypothesis, using a perceptual matching task to investigate the influence of expectations on the perceived sharpness of objects in context. Participants saw two blurred images depicting the same object and had to adjust the blur level of one object to match the blur level of the other one. We manipulated the validity of expectations about objects by varying their scene context (congruent or incongruent context leading to valid or invalid expectations about the object). We also manipulated the reliability of the visual signal by varying the initial blur level of object pairs. Results showed that expectations validity differentially affected the perception of objects depending on signal reliability. Perception of validly expected objects was enhanced (sharpened) relative to unexpected objects when visual inputs were unreliable while this effect reversed to the benefit of unexpected objects when the signal was more reliable.

It makes sense, so I see it better! Contextual information about the visual environment increases its perceived sharpness

Predictive coding theories of visual perception postulate that expectations based on prior knowledge modulate the processing of information by sharpening the representation of expected features of a stimulus in visual cortex but few studies directly investigated whether expectations qualitatively affect perception. Our study investigated the influence of expectations based on prior experience and contextual information on the perceived sharpness of objects and scenes. In Experiments 1 and 2, we used a perceptual matching task. Participants saw two blurred images depicting the same object or scene and had to adjust the blur level of the right image to match the blur level of the left one. We manipulated the availability of relevant information to form expectations about the image's content: one of the two images contained predictable information while the other one unpredictable. At an equal level of blur, predictable objects and scenes were perceived as sharper than unpredictable ones. Experiment 3 involving explicit sharpness judgments confirmed these results. Our findings support the sharpening account of predictive coding theories by showing that expectations increase the perceived sharpness of the visual signal. Expectations about the visual environment help us understand it more easily, but also makes us perceive it better. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Rapid scene categorization: From coarse peripheral vision to fine central vision

Studies on scene perception have shown that the rapid extraction of low spatial frequencies (LSF) allows a coarse parsing of the scene, prior to the analysis of high spatial frequencies (HSF) containing details. Many studies suggest that scene gist recognition can be achieved with only the low resolution of peripheral vision. Our study investigated the advantage of peripheral vision on central vision during a scene categorization task (indoor vs. outdoor). In Experiment 1, we used large scene photographs from which we built one central disk and four circular rings of different eccentricities. The central disk either contained or not an object semantically related to the scene category. Results showed better categorization performances for the peripheral rings, despite the presence of an object in central vision that was semantically related to the scene category that significantly improved categorization performances. In Experiment 2, the central disk and rings were assembled from Central to Peripheral vision (CtP sequence) or from Peripheral to Central vision (PtC sequence). Results revealed better performances for PtC than CtP sequences, except when no central object was present under rapid categorization constraints. As Experiment 3 suggested that the PtC advantage was not explained by a reduction of the visibility of the object in the central disk by the surrounding peripheral rings (CtP sequence), results are interpreted in the context of a predominant coarse-to-fine processing during scene categorization, with greater efficiency and utility of coarse peripheral vision relative to fine central vision during rapid scene categorization.

Patients' perceptions of informed consent in acute myocardial infarction research: a questionnaire based survey of the consent process in the DANAMI-2 trial

OBJECTIVE

To analyse how patients in the acute phase of a myocardial infarct experience the informed consent procedure of a clinical trial.

DESIGN

A questionnaire based follow up survey including patients who gave informed consent as well as patients who did not consent to the trial.

PATIENTS

103 patients who gave informed consent and 78 who did not consent to the second Danish acute myocardial infarction trial (DANAMI-2).

RESULTS

76% of the trial participants and 63% of the non-participants agreed or mostly agreed that they felt able to make a decision about whether or not to participate in the trial; 50% of the trial participants and 34% of the non-participants found it acceptable that patients in their situation have to make such a decision. Only 28% of the trial participants and 7% of the non-participants read the information sheet before they made the decision.

CONCLUSIONS

Informed consent should be sought in acute myocardial infarction trials despite the emergency situation and the medical condition of the patients. Patients' self assessed ability to make a decision should be explicitly addressed during the informed consent process and patients should not be pressurised into decision making. Physicians and research ethics committees should focus specifically on improving the oral information.

Patient-physician communication concerning participation in cancer chemotherapy trials

Cancer patients demand a high level of involvement in decisions concerning treatment. Many patients are informed about experimental trials, and especially the first consultation may be crucial for the future communication and treatment process. Patients with nonresectable non-small-cell lung cancer or colorectal cancer informed about experimental chemotherapy completed a questionnaire on satisfaction with the communication process, general attitude towards experimental treatments, the substance of information, and personal contact with the physician following their first consultation in a medical oncology unit. Physicians completed a questionnaire on their perception of the patients’ satisfaction. Among 68 physician–cancer patient pairs, 29 patients were informed on chemotherapy in randomised trials and 39 in nonrandomised studies. The general attitude towards experimental treatment was positive or very positive in 71% of patients. Information on the treatment was perceived as completely adequate in 93% of patients informed on randomised and in 67% informed on nonrandomised trials. Physicians underestimated the patients’ satisfaction with the overall communication process, the personal contact, the patients’ perceived sufficiency of the specific treatment information and their ability to decide on study entry. In conclusion, considerable differences were observed between patients informed about experimental chemotherapy in randomised and nonrandomised trials, both with respect to their perception of how adequate the information on the specific treatments were, and whether it was sufficient for decisions on study entry. This study type effect should be accounted for in future evaluations of communication and patient satisfaction. The data also support the fact that cancer patients have a desire for and ability to understand rather detailed and comprehensive treatment information.

Cognitive studies of ethical reasoning based on the KARDIO-simulator

Empirical investigations in medical ethics are often questionnaire studies relying on the respondents' written responses about their attitudes and actions. This approach is valuable, but there may be quite large discrepancies between responses and actual behaviour. Unfortunately actual behaviour is often difficult to observe, especially where sensitive or very time dependent clinical decisions are concerned. We have tried to circumvent this problem by using a micro-world computer simulation of a cardiac care unit to study treatment decisions in "life or death" situations. The task facing the physician in this simulation is to be in charge of a 6-bed cardiac care unit for a period of 14 "days" controlling admissions, discharges, and treatment of all patients. The simulation dynamically generates the disease states of the patients in the unit including physical findings, laboratory findings, ECG, X-ray descriptions etc., as well as the patients responses to treatment. The simulation also presents new patients from the emergency room, thereby forcing the physician to decide whether the new patient should be admitted, and whether one of the present patients should be discharged or moved to another ward if no bed is free. The paper describes this simulator, the mathematical model underlying the simulation of patients with acute myocardial infarction, and the results of the initial studies using the simulator.

Can the written information to research subjects be improved?--an empirical study

OBJECTIVES

To study whether linguistic analysis and changes in information leaflets can improve readability and understanding.

DESIGN

Randomised, controlled study. Two information leaflets concerned with trials of drugs for conditions/diseases which are commonly known were modified, and the original was tested against the revised version.

SETTING

Denmark.

PARTICIPANTS

235 persons in the relevant age groups.

MAIN MEASURES

Readability and understanding of contents.

RESULTS

Both readability and understanding of contents was improved: readability with regard to both information leaflets and understanding with regard to one of the leaflets.

CONCLUSION

The results show that both readability and understanding can be improved by increased attention to the linguistic features of the information.

[What does the Danish population know about the scientific ethics committees?]

The Danish system of research ethical committees (RECs) was established in 1978 and formal legislation on RECs was passed in 1992. We have investigated the general knowledge about the RECs through a telephone survey of a random sample of the adult Danish population. Among the 1137 respondents only 342 (30%) were aware of the existence of an official body which controls medical research, and only a small minority was aware of the composition of the RECs and that the laymembers outnumber the professional members. Knowledge about RECs was positively correlated to higher education, young age, and being male. It is argued that there is a need for increased public information about the existence and composition of the Danish RECs.