The role of loudness in auditory imagery

Four experiments studied characteristics of auditory images initiated by named but unheard sounds. The sounds varied in their loudness ratings. As the difference between the loudness ratings of the two sound phrases increased, the times to mentally equate the loudness of the two images increased, whereas the times to identify the louder (or softer) of the images decreased. Moreover, congruity effects were found in the comparative judgment task: Times were faster to identify the louder of two loud-rated stimuli than to judge the softer of the same two stimuli, and times were faster to identify the softer of the two soft-rated than two loud-rated stimuli. The loudness ratings did not always influence performance, however, for neither an image generation nor a reading task showed response times that varied with loudness ratings. These results suggest that sensory/perceptual components are optionally represented in auditory images. These components are included when appropriate to a given task. A control experiment showed that the results cannot be considered epiphenomenal.     

Interaction among auditory dimensions: timbre, pitch, and loudness

In two experiments, we examined whether or not pairs of auditory dimensions--timbre-loudness (Experiment 1) and timbre-pitch (Experiment 2)--interact in speeded classification. Subjects classified values from one dimension while the other dimension was (1) held constant (baseline), (2) varied orthogonally (filtering), or (3) correlated linearly. The subjects showed substantial Garner interference when classifying all dimensions--that is, poor performance at filtering relative to baseline. Timbre and loudness displayed redundancy gain (i.e., performance faster than baseline) when correlated positively, but redundancy loss (i.e., interference) when correlated negatively. Timbre and pitch displayed redundancy gain however dimensions were correlated. Both pairs of dimensions showed substantial effects of congruity: Attributes from one dimension were classified faster when paired with "congruent" attributes from the other dimension. The results are interpreted in terms of an interactive multichannel model of auditory processing.     

The role of attention in the formation of auditory streams

There is controversy over whether stream segregation is an attention-dependent process. Part of the argument is related to the initial formation of auditory streams. It has been suggested that attention is needed only to form the streams, but not to maintain them once they have been segregated. The question of whether covert attention at the beginning of a to-be-ignored set of sounds will be enough to initiate the segregation process remains open. Here, we investigate this question by (1) using a methodology that does not require the participant to make an overt response to assess how the unattended sounds are organized and (2) structuring the test sound sequence to account for the covert attention explanation. The results of four experiments provide evidence to support the view that attention is not always required for the formation of auditory streams.     

Power functions of loudness magnitude estimations and auditory brainstem evoked responses

The correspondence between subjective and neural response to change in acoustic intensity was considered by deriving power functions from subjective loudness estimations and from the amplitude and latency of auditory brainstem evoked response components (BER). Thirty-six subjects provided loudness magnitude estimations of 2-sec trains of positive polarity click stimuli, 20/sec, at intensity levels ranging from 55 to 90 dB in 5-dB steps. The loudness power function yielded an exponent of .48. With longer trains of the same click stimuli, the exponents of BER latency measures ranged from -.14 for wave I to -.03 for later waves. The exponents of BER amplitude-intensity functions ranged from .40 to .19. Although these exponents tended to be larger than exponents previously reported, they were all lower than the exponent derived from the subjective loudness estimates, and a clear correspondence between the exponents of the loudness and BER component intensity functions was not found.     

Control of responding by location of auditory stimuli: rapid acquisition in monkey and rat

Monkeys require a considerably larger number of trials to bring responding under the control of the location of an auditory stimulus than cats, rats, and bats with the same experimental procedures. The present experiment sought to determine the conditions necessary for rapid acquisition of control of responding by location of noise and tone bursts in the monkey. Monkeys were run in an enclosure that contained four loudspeakers and four manipulanda. Two conditions were used in training. In the adjacent condition, a stimulus (noise or tone burst) was presented through one or other of two speakers and a response on the manipulandum adjacent to the speaker was reinforced with food. In the nonadjacent condition, a stimulus was presented through one of two speakers and a response on a manipulandum remote from the speaker was reinforced with food. Acquisition of control was measured by change in the percentage of reinforced responses during training. In the adjacent condition, responding came under control of location within zero to three sessions. In nonadjacent conditions, the animals required 14 to 20 sessions to come under control of location. These latter numbers are comparable to those reported in the literature for localization discrimination in monkeys.     

Control of responding by location of auditory stimuli: adjacency of sound and response.

Four rhesus monkeys were trained to respond on one key when a one-second noise burst was presented through one speaker and to respond on a second key when the noise burst was presented through a second speaker. The acquisition of stimulus control was studied under three conditions, in each of which the relationship between the sound source and the response-key positions varied: an adjacent condition in which the noise burst was presented through the key and a response on this key was reinforced; a reversed-adjacent condition in which the noise burst was presented through one key and responding on the other key was reinforced: and a nonadiacent condition in which responding on the key nearer the sound was reinforced. Under adjacent conditions, stimulus control developed within one or two sessions. Under reversed and nonadjacent conditions, 10 sessions were required for the development of control. The asymptote of correct responding was the same under each condition in all animals.     

Control of responding by the location of an auditory stimulus: role of rise time of the stimulus

The control of responding by the location of tone bursts of 0.2- or 50-msec rise time was investigated in three albino rats. The apparatus consisted of an enclosure with two levers, two loudspeakers (in different locations), and a dipper feeder. The animal was exposed to tone bursts from either one or the other of the two speakers, and the speaker through which the tone bursts were delivered on any particular trial alternated in an irregular manner. Responses on one lever were reinforced with food in the presence of tone bursts from one speaker; responses on the second lever were reinforced with food in the presence of tone bursts from the second speaker. Responding came under the control of the location of 4-kHz tone bursts of 0.2-msec rise time within the first session. At this rise time, animals maintained a stable level of correct responding of greater than 95%. When the rise time was increased to 50 msec the percentage of correct responding fell to an average of 80 to 85%. It was concluded that location of an auditory stimulus is a powerful controller of responding in rats and that the degree of control is dependent upon rise time.     

Cross-modality matching of brightness to loudness by 5-year-olds

The purpose was to determine whether 5-year-old children could match the brightness of a light to the loudness of a sound, and whether the resulting cross-modality function resembled the power function produced by adults. Each of five children adjusted the voltage on a 15D-W lamp to make the apparent brightness appear equal to the loudness of a 500-Hz tone, which the E set to eight different levels. The results resembled those of five adults who performed the same task.     

The cross-modal matching of brightness to loudness by children

According to Stevens' explanation of cross-modal matching, the recruitment-like effects of masking seen in intramodal loudness judgements should be reflected in a brightness-to-loudness matching task. In an experiment with child observers, this failed to occur. The results are explicable in terms of category mediation of the cross-modal, but not the intramodal, task. In support of this account, it is shown that cross-modal judgements are unaffected by explicit category mediation. However, intramodal judgements, explicitly mediated in the same way, produce a pattern of results similar to those obtained in the cross-modal task. The experiments suggest that cross-modal matching does not provide a useful test of loudness recruitment in the bilaterally hearing impaired.     

Identification of visual stimuli is improved by accompanying auditory stimuli: the role of eye movements and sound location

Can auditory signals influence the processing of visual information? The present study examined the effects of simple auditory signals (clicks and noise bursts) whose onset was simultaneous with that of the visual target, but which provided no information about the target. It was found that such a signal enhances performance in the visual task: the accessory sound reduced response times for target identification with no cost to accuracy. The spatial location of the sound (whether central to the display or at the target location) did not modify this facilitation. Furthermore, the same pattern of facilitation was evident whether the observer fixated centrally or moved their eyes to the target. The results were not altered by changes in the contrast (and therefore visibility) of the visual stimulus or by the perceived utility of the spatial location of the sound. We speculate that the auditory signal may promote attentional 'disengagement' and that, as a result, observers are able to process the visual target sooner when sound accompanies the display relative to when visual information is presented alone.     

Infants' formation and use of categories to segregate objects

Four- and-a-half-month-old infants' (N = 100) category formation and use was studied in a series of five experiments. For each experiment, the test events featured a display composed of a cylinder and a box. Previous research showed that this display is not clearly parsed as a single unit or as two separate units by infants of this age. Immediately prior to testing, infants were shown a set of category exemplars. Knowledge about this category could help infants disambiguate the test display, which contained a novel exemplar of this category. Clear interpretation of the test display as composed of two separate units (as indicated by infants' longer looking at the move-together than at the move-apart test event) was taken as evidence of category formation and use. In Experiments 1 and 5, infants' prior experience with a set of three different boxes that were similar to the test box facilitated their segregation of the test display. Experiment 2 showed that three different exemplars are necessary: prior experience with any two of the three boxes used in Experiment 1 did not facilitate infants' segregation of the test display. Experiment 3 showed that variability in the exemplar set is necessary: prior experience with three identical boxes did not facilitate infants' segregation of the test display. Experiment 4 showed that under these conditions of very brief prior exposure, similarity between the exemplar set and test box is necessary: prior experience with three different boxes that were not very similar to the test box did not facilitate infants' segregation of the test display. Together, these findings suggest that: (a) number of exemplars, variability, and similarity in the exemplar set are important for infants' category formation, and (b) infants use their category knowledge to determine the boundaries of the objects in a display.     

Encoding location and serial order in auditory working memory: evidence for separable processes

In this study, we investigated the interactions between temporal and spatial information in auditory working memory. In two experiments, participants were presented with sequences of sounds originating from different locations in space and were then asked to recall either their position or their serial order. In Experiment 1, attention during encoding was manipulated by contrasting 'pure' blocks (i.e., location-only or serial-order-only trials) to 'mixed' blocks (i.e., different percentages of spatial and serial-order trials). In Experiment 2, 'pure' blocks were contrasted to blocks in which spatial and serial-order trials were intermixed with a third task requiring a semantic categorization of sounds. Results from both experiments showed that, whereas serial-order recall is linearly affected by the simultaneous encoding of a concurrent feature, the recall of position is mostly unaffected by concurrent feature encoding. Contrastingly, overall performance level was lower for spatial recall than serial recall. We concluded that serial order and location of items appear to be independently encoded in auditory working memory. Serial order is easier to recall, but strongly affected by the processing of concurrent item dimensions, while item location is more difficult to recall, but relatively automatic, as shown by its strong resistance to interfering dimensions in encoding.     

Continuous judgment of level-fluctuating sounds and the relationship between overall loudness and instantaneous loudness

Summary The present investigation was designed to examine the most appropriate duration of instantaneous loudness and to find out the relationship between overall loudness and instantaneous loudness using 20-min road traffic noise. Instantaneous loudness was judged using the method of continuous judgment by category. The results suggest that instantaneous loudness is determined by the sound energy averaged during the 2.5-s period preceding each judgment, the duration of which seems to reflect the psychological present. It was also found that overall loudess is not an average of the instantaneous loudness of every moment, but that it is based on the instantaneous loudness above a certain level.     

Age-related changes in aphasia type and stroke location

Two-hundred consecutive CT scans of patients with an infarction in the territory of the middle cerebral artery (MCA) were examined for evaluation of a possible relationship between age and stroke location. Two distinct procedures, one evaluating the incidence of four areas within the MCA territory and the other measuring some quantified parameters, were used. Statistical studies failed to show any significant correlation between these parameters and the age of patients. These results lead to refute previous claims that semiological changes in aphasia type with age in stroke patients may be due to a posterior shift of cerebral infarcts with age.     

Personality and the slope of loudness function

The slope of the loudness function in direct magnitude estimation was studied at two frequencies in two groups of naive subjects. In the first group a limited scale was used and in the second group, an open ended scale. In all conditions the slope of the loudness function was found to be significantly positively correlated with test anxiety scores.     

Brighter noise: Sensory enhancement of perceived loudness by concurrent visual stimulation

Two experiments investigated the effect of concurrently presented light on the perceived loudness of a low-level burst of white noise. The results suggest two points. First, white noise presented with light tends to be rated as louder than noise presented alone. Second, the enhancement in loudness judgments is resistant to two experimental manipulations: varying the probability that light accompanies sound and shifting from a rating method to a forced choice comparison. Both manipulations were previously shown to eliminate a complementary noise-induced enhancement in ratings of brightness. Whereas noise-induced enhancement of brightness seems to reflect a late-stage decisional process, such as a response bias, the present results suggest that light-induced enhancement of loudness may reflect an early-stage sensory interaction.     

Reducing the tendency to self-handicap: The effect of self-affirmation

Self-handicapping, the creating or claiming of obstacles to one’s performance to influence explanations given for subsequent outcomes, has been shown to have a host of attitudinal and behavioral consequences. Given the wide ranging impact of self-handicapping, it is important to understand the conditions under which self-handicapping is more or less likely to occur. Accordingly, the present study tested the hypothesis that people will be less likely to engage in self-handicapping if they have previously engaged in self-affirmation. The results of this study found that self-affirmation was more effective in reducing self-handicapping behavior when individuals experienced non-contingent success than when they experience contingent success. Theoretical contributions to the self-handicapping and self-affirmation literatures are discussed, as are practical implications.