Spatial stimulus cue information supplying auditory saltation

Auditory saltation is a misperception of the spatial location of repetitive, transient stimuli. It arises when clicks at one location are followed in perfect temporal cadence by identical clicks at a second location. This report describes two psychophysical experiments designed to examine the sensitivity of auditory saltation to different stimulus cues for auditory spatial perception. Experiment 1 was a dichotic study in which six different six-click train stimuli were used to generate the saltation effect. Clicks lateralised by using interaural time differences and clicks lateralised by using interaural level differences produced equivalent saltation effects, confirming an earlier finding. Switching the stimulus cue from an interaural time difference to an interaural level difference (or the reverse) in mid train was inconsequential to the saltation illusion. Experiment 2 was a free-field study in which subjects rated the illusory motion generated by clicks emitted from two sound sources symmetrically disposed around the interaural axis, ie on the same cone of confusion in the auditory hemifield opposite one ear. Stimuli in such positions produce spatial location judgments that are based more heavily on monaural spectral information than on binaural computations. The free-field stimuli produced robust saltation. The data from both experiments are consistent with the view that auditory saltation can emerge from spatial processing, irrespective of the stimulus cue information used to determine click laterality or location.     

Pigeons' preferences for stimulus information: effects of amount of information

A concurrent-chain procedure was used to study pigeons' preferences as a function of amount of information. Pigeons chose between two terminal links. Both terminal links ended in food reinforcement with probability (p) and in blackout with probability (1–p). One terminal link (noninformative link) was signalled by a stimulus uncorrelated with either food or blackout. The other terminal link (informative link) was signalled by stimuli correlated with these outcomes. Amount of information conveyed by these stimuli was varied across conditions by changing the probability of reinforcement (p) and blackout (1–p). The pigeons strongly preferred the informative link, and preferences were greater at p values above 0.50 than for their complements. The pigeons engaged in different behaviors during the stimulus periods, suggesting that the value of informative stimuli may be in their function as discriminative stimuli for interim activities and terminal responses.     

Modality-specific interference with verbal and nonverbal stimulus information

Subjects recalled both letters and the locations of letters in 2 by 3 and 1 by 6 matrices after either no interfering activity or visual, auditory, or kinesthetic interfering activity. Results for each type of matrix indicated the presence of selective auditory (verbal) interference with the recall of letter identity and selective visual and kinesthetic interference with the recall of letter location. Supplementary correlational analyses indicated that the presence of such a dual encoding strategy was most consistent across subjects for the 2 by 3 matrix. Although the results indicated that use of different modes of representation was related to the verbal-nonverbal nature of the information, it was shown that the structure of the stimulus array also affected the nature of the representation.     

Use of partial stimulus information in response processing

We examined the reaction time benefit that is obtained when salient features of the stimulus set and response set correspond. Components of the event-related brain potentials were used to measure the timing of stimulus-related and response-related processes in order to determine the locus of this effect. Of particular importance was the development of a new index of selective response preparation, the corrected motor asymmetry (CMA). We found no evidence for the use of preliminary, partial stimulus information in response preparation. These results suggest that the benefit is located primarily in response selection processes and probably reflects a more efficient algorithm for stimulus-response translation. Also, we found trial-to-trial variability in the duration of response selection to be the major determinant of variability in reaction time, whereas the durations of subsequent response-related processes were relatively invariant. Implications of these results for discrete and continuous models of choice reaction performance are discussed.     

Stimulus information and primate discrimination learning: The influence of postresponse stimulus information

This paper describes an experiment concerned with the operation of discriminatory processes subsequent to an individual's overt choice response and how these may be affected by extrinsic stimulus information. The experiment used subhuman primates and was conducted within the simultaneous two-choice visual discrimination paradigm. The major results of the experiment indicated that: (1) learning performance may be significantly interfered with by irrelevant postresponse stimulus information, and (2) this interference is primarily associated with the presentation of irrelevant information subsequent to nonreinforced choice responses. The results are discussed in terms of the relation between the occurrence of reinforcement and the operation of memory storage processes.     

Stimulus information and stimulus interference in bisensory short-term memory

An attempt was made to determine if Ss’ strategy of retaining stimulus material changed under conditions of bisensory simultaneous stimulation when one of the two inputs was relevant information as opposed to interference. Thus in Group 1 Ss were stimulated bisensorily, attended to both inputs (information), but recalled only one input. Ss in Group 2 were stimulated bisensorily, attended to only one input, and recalled only that input (interference). It was found that S’s efficiency of recall was decreased in the information condition (Group 1) but strategy was not altered. In both groups, Ss performed similarly; performance was in turn similar to that observed in the typical bisensory situation, i.e., where both channels are recalled.     

The use of correlated stimulus information in card sorting

Subjects were required to sort three packs of cards into six piles. On the cards of one pack were a number (one to six) of xs. In the second pack the cards had a single digit (1 to 6). On the third pack the two kinds of information were perfectly correlated, i.e., there were three 3s, four 4s, etc. This pack was sorted more quickly than either of the other two. It is provisionally concluded that the Ss were processing information in parallel rather than serially, and that evidence from two sensory analyzers was being combined rather than the outcome from two decision mechanisms. This conclusion is tempered by the observation that only a detailed study of the reaction times to individual stimuli can provide us with an unqualifled verdict.     

A visual object stimulus database with standardized similarity information

Although many visual stimulus databases exist, none has data on item similarity levels for multiple items of each kind of stimulus. We present such data for 50 sets of grayscale object photographs. Similarity measures between pictures in each set (e.g., 25 different buttons) were collected using a similarity-sorting method (Goldstone, Behavior Research Methods Instruments & Computers, 26(4):381–386, 1994). A validation experiment used data from 1 picture set and compared responses from standard pairwise measures. This showed close agreement. The similarity-sorting measures were then standardized across picture sets, using pairwise ratings. Finally, the standardized similarity distances were validated in a recognition memory experiment; false alarms increased when targets and foils were more similar. These data will facilitate memory and perception research that needs to make comparisons between stimuli with a range of known target–foil similarities.     

Activation of response codes by relevant and irrelevant stimulus information

Single-route models attribute stimulus-response compatibility effects to the difficulty of translation from stimulus to response. Dual-route models propose that compatibility effects reflect in part an additional direct, or automatic, activation route. Selected findings from three lines of research are reported that converge to provide evidence consistent with the view that the automatic activation route plays a role in compatibility effects. The data suggest that the activation produced via this route by relevant stimulus attributes influences response selection only when all mappings of stimuli to responses are known to be compatible.     

无意识信息的刺激表征及其时间特性

无意识信息是否存在刺激表征有待解决。实验采用字母Flanker任务, 通过目标和flanker在刺激水平和反应水平上的冲突效应, 重点考察阈下flanker在刺激水平的表征。在相同的实验设计下, flanker可觉察时(实验1A), 观察到经典的刺激冲突效应和反应冲突效应; 而flanker无意识时(实验1B), 重复了反应冲突效应, 却观察到刺激冲突效应发生反转, 提示了无意识信息的反应加工及刺激加工。实验2采用符号材料促使刺激−反应的自动联结, 减少刺激−反应规则的难度, 结果重复了实验1B的发现--无意识信息引起反转的刺激冲突。刺激冲突下反转效应的一致结果表明无意识信息的刺激表征影响了认知加工。实验3考察这种影响在时间进程上的特点。无意识刺激表征的影响随反应时变化：在快速反应中观察到刺激冲突效应, 之后该效应发生反转且反转量随反应时增加而增大。相反, 无意识反应表征的影响在不同反应时下保持稳定。以上结果提供了无意识信息存在刺激表征的行为学证据并揭示了其时间特性, 提供了无意识领域中不一致研究结果的整合思路。     

The effect of stimulus complexity on retrieval of information frown memory

Eighteen Ss performed an item recognition task involving memorized lists of one, two, and three nonsense forms at one of two levels of stimulus complexity. Analysis of RT-set size functions and serial position functions suggested that (a) when the memorized list consisted of simple figures, Ss engaged in a serial exhaustive search of items stored in memory prior to responding and (b) when the memorized items were complex, an increase in set size was accompanied by a change in search strategy from a backward self-terminating search to a random self-terminating search.     

The temporal distribution of stimulus information in the visual evoked potential

Research in psychophysics (Bloch's law) and perceptual experiments concerned with the integration of successively presented stimuli suggest that the perception of form is a process that occurs over a period of as much as 200-300 msec. Such results prompted the question of whether the visual evoked potential (VEP) might contain information about the distribution over time of perceptual processing. Subjects viewed lines formed from combinations of three lengths and four angles while the EEG was recorded. Analysis of the VEPs indicated that the length and angle of the lines produced temporal distributions of information in the VEP and that the distributions for length and angle were somewhat different. The major difference was that the processing of angle begins earlier and is completed sooner than the processing of length. A conclusion of the experiment was that an alternative or supplement to analyzing VEPs for specific waveform features is to consider the encoding of stimulus information in the VEP as a density or concentration over time.     

Cognitive precedence for local information in hierarchical stimulus processing by pigeons

Four experiments investigated the processing of hierarchical stimuli by pigeons. Using a 4 alternative divided-attention task, 4 pigeons were food-reinforced for accurately identifying letters arranged as either hierarchical global- or local-relevant stimuli or as size-matched filled stimuli. Experiment 1 found that task acquisition was faster with local-relevant than global-relevant stimuli. This difference was not due to letter size. Experiment 2 demonstrated successful transfer to a novel irrelevant letter configuration. Experiments 3 and 4 tested pigeons' responses to conflict probe stimuli composed of equally discriminable relevant letters at each level. These tests revealed that all of the pigeons showed a cognitive precedence for local information early in processing, with the pigeons using different cues to initiate the processing of global information. This local advantage contrasts with previously reported results for humans and pigeons but is similar to that reported for nonhuman primates. Alternatives attempting to reconcile these contrasting comparative results are considered.     

Effects of stimulus and contextual information on the lexical decision process

Two experiments were conducted to investigate context effects on the lexical decision process. In both experiments, observers classified letter strings as words or nonwords following the presentation of context in the form of an incomplete sentence. In Experiment 1, the predictability of congruous word stimuli and their frequency of occurrence in printed English were varied. These two factors had independent and additive effects on decision latencies. Stimulus quality, word frequency, and semantic congruity (i.e., congruous vs. incongruous) between the context and the stimulus were varied in Experiment 2. The effects of semantic congruity and word frequency on decision latencies combined additively, as did the effects of semantic congruity and stimulus quality. Two complementary mechanisms were proposed within the framework of a modified version of Becker’s verification model to account for the differential effects of single-word and sentence context priming on the lexical decision process.     

Interhemispheric interaction when both hemispheres have access to the same stimulus information

Right-handed Ss identified consonant-vowel-consonant (CVC) nonsense syllables presented tachistoscopically. The CVC on each trial was presented to the left visual field-right hemisphere (LVF-RH), to the right visual field-left hemisphere (RVF-LH), or the same CVC was presented to both visual fields (bilateral presentation). When recognition was incorrect, the pattern of errors was qualitatively different on LVF-RH and RVF-LH trials, suggesting that each cerebral hemisphere has its own preferred mode of processing the CVC stimuli. The qualitative pattern of errors on bilateral trials was identical to that obtained on LVF-RH trials. The bilateral results are described well by a model that assumes the mode of processing characteristic of the RH dominates on bilateral trials but is applied to both the LVF-RH and RVF-LH stimuli.     

The effects of stimulus dimensionality on the rate of gain of information

Hick's paradigm as extended to an absolute judgment task by Doherty was used to study the effects of dimensionality on the rate of stimulus identification in two experiments. Two undimensional conditions, size and brightness, and two bidimensional conditions, size-brightness redundant and size-brightness non-redundant, were employed. The significant linear components of the regression of choice reaction time on transmitted information for the undimensional and bidimensional stimuli supported and extended Hick's law. The finding of nearly identical slopes for the two undimensional and redundant bidimensional condition regression lines suggests a stage of processing which has a constant capacity in bits/s and which is independent of stimulus dimensionality. An increase in slope for the non-redundant condition is attributed to a difference in response requirements.