Many recent investigators have studied "Response Bias" theories of the perception of common vs. uncommon words. 4 different classes of theory are distinguished, and it is demonstrated that 3 of them are inconsistent with previously published and with fresh data. The 4th sense of response bias, however, leads to the prediction that bias on correct responses may be greater than that on errors, and is very accurately consistent with the data. This is the sense of response bias as analogous to the bias of a criterion in a statistical decision.

Performance involves numerous sub‐functions, and cannot be treated as a unit. Several attempts have been made to separate functions impaired by different classes of drug: for example, high (monitoring) vs lower (performing) levels of function, early (perceptual) vs later (motor) functions, and strategic vs executive functions. The practical implications are that one cannot predict effects of a drug from a single performance test. One must either simulate the practical situation exactly, or use a battery of analytical tests to form a profile of effects. The latter is the policy urged in this paper.

No abstract

541way, noise moving to the leeward side of the source is deflected upwards, and beyond a certain distance on the leeward side it is impossible to hear a source however intense it may be. Fig. 5 illustrates these effects.This question of the effect of a wind on noise may at first sight appear to be of relatively small importance, but it is conceivable that it could be utilized with advantage. For example, if domestic dwellings and offices are located on the windward side of airfields and factories (as far as prevailing winds are concerned), the noise nuisance is likely to be less severe on the FIG. s. EFFECT OF WIND average. Noisy running tests FIG. 5.could also be arranged as far as possible when atmospheric conditions favour the least nuisance due to noise. V-CONCLUSIONIn conclusion, it can be said that the problems of noise and its alleviation are varied ones dependent on individual conditions. By attacks on the problems from all possible angles, it is often possible to achieve a worth-while degree of success.As soon as we begin to think about noise and behaviour, we have to consider what &dquo;~ kind of evidence we shall regard as satisfactory. For, as K. D. Kryter says in the best review of the subject yet writteni: &dquo; Viewed from a scientific aspect, a great number of publications in this field represent poorly designed experiments or unsupported opinions.&dquo; To be accepted by the strict scientist, any work on the effects of noise must fulfil at least three conditions. Firstly, it must show results which are objective, rather than opinions; records of accidents, output, admissions to hospital, and so on are acceptable while the judgment of people who work in noise is not. The reason for this is simply that judgment is one of the first human functions to be disturbed by any stress. For example, one of the greatest dangers from oxygen lack affecting pilots at great heights, is that the victim does not detect his own growing inefficiency. Conversely, people often blame innocent causes for ine~ciency due to other reasons: &dquo; the bad workman blames his tools.&dquo; So a man may assure us that he is unaffected by noise, or that he is crippled by it, but in neither case can we trust his word alone.The second rule which must be satisfied is that the results should not be due to chance.If we toss a penny once and it comes down heads, we would hardly be justified in assuming that the penny was weighted: we would have to toss it at least six times and get heads every time before our suspicions were aroused. Similarly, if Mr. Jones works well on Monday in quiet, but badly on Tuesday with a pneumatic drill outside his window, we can draw no scientific conclusion. Mr. Brown might have showed the opposite effect; even Mr. Jones might have behaved differently if the days had been Friday and Saturday. There are ways of calculating the level of confidence which can be felt in