Same-different reaction times studied with a flash masking technique

The reaction times (RT) needed to report whether letters were the same or different were measured using a very long exposure of the target and a very brief exposure of a flash mask. Two letters were presented simultaneously in Experiment 1. No effect of response category (same vs. different) was found, although a clear-cut luminance-dependent masking effect was present. Letter number was manipulated in Experiment 2. A three-way interaction was found among response category, number of letters, and stimulus onset asynchrony (SOA). The more difficult task produced longer RTs for “different” judgments than for “same” judgments, particularly at intermediate SOAs. These data are compared with information processing models of perception.     

Temporal integration of vibrotactile patterns

Three experiments were conducted to measure the temporal integration of vibrotactile patterns presented to the fingertip. In Experiment 1, letters were divided in half and the time between the onsets of the first half of the letter and second half of the letter, stimulus onset asynchrony (SOA), was varied. The recognizability of the letters declined as the SOA was increased from 9 to 100 msec. In Experiment 2, the time between two patterns constituting a masking stimulus was varied and the stimulus effectiveness in interfering with letter recognition was determined. The amount of masking increased as the SOA increased from 9 to 50 msec. In Experiment 3, the SOA between a letter and its complement (the portions of the tactile array not activated by the letter) was varied. Increasing SOA from 9 to approximately 50 msec led to increasingly accurate letter recognition. The results of the three experiments suggest that the skin is capable of complete temporal integration over a time period of less than 10 msec, and that the temporal integration function becomes asymptotic in 50 to 100 msec. The results also suggest that the onset of a vibrotactile pattern is critical for generating contours. The implications of the results for modes of generating tactile patterns and for temporal masking functions are discussed.     

Vibrotactile masking: A comparison of energy and pattern maskers

Subjects were required to identify vibrotactile patterns presented to their fingertips. The patterns, letters of the alphabet, were presented singly or in the presence of other vibrotactile masking stimuli. Two types of masking stimuli were used: an energy masker and a pattern masker. The effectiveness of these two types of maskers in interfering with letter recognition was tested, using them as forward and as backward maskers and presenting them at several different levels of intensity. The results showed more masking by the pattern masker, more backward than forward masking, and more masking as intensity increased. In addition, compared with the energy masker, the pattern masker showed both a greater difference between forward and backward masking and a greater increase in masking as masker intensity increased. The results are discussed in terms of a two-factor model of vibrotactfle masking.     

The control of stimulus-driven saccades is subject not to central, but to visual attention limitations

In three experiments, we investigated whether the control of reflexive saccades is subject to central attention limitations. In a dual-task procedure, Task 1 required either unspeeded reporting or ignoring of briefly presented masked stimuli, whereas Task 2 required a speeded saccade toward a visual target. The stimulus onset asynchrony (SOA) between the two tasks was varied. In Experiments 1 and 2, the Task 1 stimulus was one or three letters, and we asked how saccade target selection is influenced by the number of items. We found (1) longer saccade latencies at short than at long SOAs in the report condition, (2) a substantially larger latency increase for three letters than for one letter, and (3) a latency difference between SOAs in the ignore condition. Broadly, these results match the central interference theory. However, in Experiment 3, an auditory stimulus was used as the Task 1 stimulus, to test whether the interference effects in Experiments 1 and 2 were due to visual instead of central interference. Although there was a small saccade latency increase from short to long SOAs, this difference did not increase from the ignore to the report condition. To explain visual interference effects between letter encoding and stimulus-driven saccade control, we propose an extended theory of visual attention.     

Enhancement,extension, and reversal of the frequency selectivity effect

The influence of a frequency cue on judgments of whether or not a subsequent target incorporated a brief silent gap was examined. In Experiment 1, there was no predictive frequency relation and evidence of auditory inhibition of return was obtained with frequency repetitions, producing a facilitative effect at 175-msec stimulus onset asynchrony (SOA) and an inhibitory effect at 775-msec SOA. Relative to this baseline performance pattern, increasing the probability of a frequency match to .75 (Experiment 2) served to generate a beneficial effect of frequency repetitions at lengthy SOAs and to enlarge its magnitude at 175-msec SOA. In contrast, a reduction in the probability of a frequency match to .25 (Experiment 3) resulted in the elimination of any facilitative effect of repetition at 175-msec SOA and the development of an inhibitory effect at 475- and 1,075-msec SOA. These results establish that a frequency cue may engage both exogenous and endogenous attentional processes within 175 msec following its presentation.     

Associative strength effects in the lexical decision task

Four experiments explore the role of automatic and attentional processing in producing strength effects in a lexical decision task. Experiment I manipulated the relative proportion of related and unrelated pairs, the stimulus-onset-asynchrony (SOA), and the strength of the prime-target relationship. Results indicated that strength was independent of the proportion of related and unrelated pairs and SOA. Experiment 2 manipulated the relative proportion of strong and weak related pairs and the strength of the prime-target relationship at a relatively long SOA interval (500 msec). Results showed that the strength effect was present when more strong than weak pairs were presented, and it was absent when the stimulus list contained more weak than strong pairs. Experiment 3 replicated the more weak pairs condition of Experiment 2 but with a short SOA interval (100 msec) and showed that the strength effect was found regardless of the large number of weak related pairs presented. Experiment 4 manipulated strength of the prime-target relationship and proportion of strong and weak pairs but introducing a neutral prime condition and a longer SOA interval (1000 msec). Results are discussed within a two-process model (Posner & Snyder, 1975) postulating that the strength effect at short SOAs is due to automatic processes, whereas at long SOAs it is due to the influence of attentional processes.     

Long-term facilitation of return: A response-retrieval effect

The present study used a target–target procedure to examine the extent to which perceptual and response factors contribute to inhibition of return (IOR) in a visual discrimination task. When the target was perceptually identical to the previous target and the required response was the same, facilitation was observed for both standard and long-term target–target stimulus onset asynchronies (SOAs). When the color of the previous target differed from that of the current target but the response remained the same, facilitation was reduced in both the standard SOA and long-term SOA conditions. Finally, IOR was observed for both standard and long-term SOAs only in the condition in which there was a change in response. This pattern of inhibition and facilitation provides new evidence that the responses previously associated with a location play an important role in the ability to respond to a stimulus. We interpret this finding as consistent with a framework in which the involuntary retrieval of bound stimulus–response episodes contributes to response compatibility effects in visual stimulus discrimination.     

Repetition in visual word identification: Benefits and costs

University students performed lexical tasks with visually presented target words after the presentation of an identical or unrelated prime, at short (80–120?ms) or longer (410–710?ms) prime–target stimulus onset asynchronies (SOAs). Experiment 1 showed perceptual identification benefits in vocal responding at a short SOA that were reduced (accuracy) or reversed (latency) at a longer SOA. Experiment 2 showed a transition from a repetition benefit to a cost over 3 SOAs in a target-masked version of the lexical decision task (LDT; target displayed for only 141?ms). In Experiment 3 the repetition cost was replicated at a 530-ms SOA in the LDT with masked targets, but a repetition benefit was observed in the conventional LDT (target displayed until response). The dependence of repetition costs on target masking is more consistent with biases based on episodic confusions than refractoriness of lexical representations.     

On the nature of the affective priming effect: Effects of stimulus onset asynchrony and congruency proportion in naming and evaluative categorization

In line with the hypothesis that affective priming of evaluative categorization responses is based on processes that operate at a response selection stage, it has been observed that increasing the proportion of congruent trials brings about increased affective priming effects at short stimulus onset asynchronies (SOAs) in the evaluative categorization task. In the present study, we orthogonally manipulated the congruency proportion (.25, .50, and .75) and the SOA (0, 200, and 1,000 msec) in the evaluative categorization task and a naming task. Results showed that at both short and long SOAs, the affective priming effect in the evaluative categorization task was influenced by the congruency proportion. In contrast, affective priming effects in the naming task were unaffected by the congruency proportion at short SOAs. This pattern of results provides corroborating evidence for the hypotheses (1) that different processes underlie the affective priming effect in the evaluative categorization task and the naming task and (2) that valenced stimuli can automatically preactivate the memory representations of other, affectively related stimuli.     

Large and rapid improvement in form discrimination accuracy following a location precue

Processing of a visual stimulus can be improved by precuing its location. Most previous precue studies have used reaction time as the dependent measure and have found large effects; but when form discrimination accuracy has been used, precue effects have been relatively small. The present experiments yielded large, short-latency precue effects on form discrimination accuracy. A small square precue was briefly presented near one of four possible target locations. Then one of four possible targets (T-like figures) was presented in each location, followed by a mask. Observers attempted to identify the target that had been presented in the cued location. In experiment 1, target duration, cue-to-target distance, and cue-target onset asynchrony (SOA) were varied. Target discriminability (d') increased markedly with increasing precue-target SOA, even at very short SOAs. Thus, there was no evidence for a delay in the onset of precue effects (caused, for example, by the need to shift attention across the visual field). Performance was best for precues that were closest to the target, thus ruling out a forward masking explanation of the effect. Finally SOA and target duration interacted strongly - longer precue SOAs resulted in larger effects of target duration. In experiment 2, this interaction was replicated using an additional target duration and longer SOAs. One interpretation of this result is that focal attention increases the rate at which information can be extracted from a visual location.     

Inhibition of return for the length of a line?

Inhibition of return is most often measured using an exogenous spatial cuing method. The experiments presented here follow up on a small number of studies that have examined whether a similar effect occurs for nonspatial stimulus attributes. In Experiments 1 and 2, the task was to identify a target line as either short or long. In this context, targets on valid trials were of the same length as that of a preceding cue, whereas targets on invalid trials were of a different length than that of a preceding cue. The results were similar to those in spatial orienting studies in that responses were slower for valid than for invalid targets only at stimulus onset asynchronies (SOAs) longer than 300 msec. In Experiment 3, the stimuli were the same but the task was to detect the onset of the target line. This task change resulted in slower responses for valid than for invalid targets at all SOAs. A similar result was observed in Experiment 4, in which validity was defined by color rather than line length, and the task was to identify the target color. The discussion centers on an opponent process approach to interpreting cuing effects, and consequent difficulties in distinguishing spatial and nonspatial cuing effects based on their time course.     

Interference in localizing tactile stimuli

A series of experiments investigated the ability of subjects to localize a tactile stimulus in the presence of an additional, extraneous tactile stimulus. The subject's task was to localize a tactile stimulus (target) presented at one of several locations on his or her left index fingerpad. The target stimulus, generated on a 6 x 24 array of stimulators, was presented either by itself or in the presence of an extraneous stimulus (masker) that either preceded or followed the target. The localizability of the target was affected by the temporal separation between the target and masker in much the same way as previous studies have shown identification of tactile patterns to be affected. Unlike previous identification results, presenting the masking stimulus to the same location as the target interfered with localizability, although not as much as did presenting the masker to a different location. The results are discussed in terms of their implications for identification and discrimination of tactile patterns.     

Graded aspects of morphological processing: task and processing time

Effects on targets of orthographically (O) and semantically (S) related primes were compared with morphologically related (M) primes in the lexical decision, naming, and go/no go naming tasks. The overall pattern typified the graded nature of morphological processing. Morphological relatedness produced facilitation whose magnitude varied across a range of stimulus onset asynchronies (SOAs of 66-300 ms) and tasks. The effect of semantic and orthographic similarity also depended on SOA and on task. Importantly, the effects of morphological relatedness and orthographic similarity diverged along a time course that reflected semantic processing but could only be approximated by the effect of semantic relatedness between prime and target.     

Facultative and inhibitory effects of location and frequency cues: Evidence of a modulation in perceptual sensitivity

The possibility that facilitative and inhibitory effects of auditory cues result because of a modulation in perceptual sensitivity was examined. Listeners were presented with a cue followed by a target, with the time period between the two varied at stimulus onset asynchronies (SOAs) of 150,450, or 750 msec. In two conditions, the cue and target were either the same or different in location or frequency. In both conditions, listeners were required to identify the rise time of the target. Whereas the cue was presented in isolation, the target was presented in a wide-band noise background such that the required discrimination was made relatively difficult. In both conditions, a facilitative effect was apparent at the 150-msec SOA and an inhibitory effect was apparent at the 750-msec SOA for both accuracy and response time measures of performance. That these results were apparent for a judgment unrelated to the manipulated cue-target relation suggests strongly that both location-based and frequency-based auditory inhibition of return result primarily because of changes in perceptual sensitivity.     

Temporal characteristics of the surprise reaction induced by schema-discrepant visual and auditory events

Abstract

Two experiments investigated the effects of a schema-discrepant event on the surprise reaction. Schema-discrepancy concerned a physical feature of irrelevant distractor words that were presented while the subjects performed a choice reaction time task. The stimulus onset asynchrony (SOA) between the distractors and the task-relevant stimuli was manipulated in both experiments. The occurrence of the schema-discrepant event led to subjective feelings of surprise and enhanced recall of the stimulus material. In Experiment 1, the presentation of a schema-discrepant auditory event resulted in a pronounced increase of reaction time (RT) with a 0.2sec SOA but not with a 1.5sec SOA. In Experiment 2, the effects of both fixed and variable SOAs of four different lengths (simultaneous onset, 0.5sec, 1sec, or 2sec SOA) were investigated within a visual task context. The increase of RT was found to be most pronounced with SOAs of 0.5sec and lsec respectively, and more pronounced with variable than with fixed SOAs, especially with a simultaneous onset. These results provide information about the temporal characteristics of the inhibitory component of the surprise reaction, and suggest that the inhibitory effects of surprise depend considerably on the subjects' state of preparation for the experimental task.     

Semantic aspects of morphological processing: transparency effects in Serbian

We examined the contribution of semantics to morphological facilitation in the visual lexical decision task at two stimulus onset asynchronies (SOAs) with Serbian materials. Primes appeared in Roman or Cyrillic characters. Targets always were printed in Roman. When primes were presented at an SOA of 250 msec, decision latencies to verbal targets (e.g., VOLIM) showed greatest facilitation after inflectionally (e.g., VOLE) related primes, significantly less after semantically transparent derived primes (e.g., ZAVOLE), and less again after semantically opaque derived primes (e.g., PREVOLE). Latencies after semantically transparent and opaque derived target words did not differ at an SOA of 48 msec. Both were slower than after inflectionally related primes. Stated generally, effects of semantic transparency among derivationally related verb forms were evident at long SOAs, but not at short ones. Under alphabet-alternating conditions, magnitudes of facilitation were greater overall, but the pattern was similar. The outcome suggests that restricted processing time for the prime limits the contribution of semantics to morphological processing and calls into question accounts that posit a task-invariant semantic criterion for morphological decomposition within the lexicon.     

Facilitative and inhibitory effects of location and frequency cues: evidence of a modulation in perceptual sensitivity.

The possibility that facilitative and inhibitory effects of auditory cues result because of a modulation in perceptual sensitivity was examined. Listeners were presented with a cue followed by a target, with the time period between the two varied at stimulus onset asynchronies (SOAs) of 150, 450, or 750 msec. In two conditions, the cue and target were either the same or different in location or frequency. In both conditions, listeners were required to identify the rise time of the target. Whereas the cue was presented in isolation, the target was presented in a wide-band noise background such that the required discrimination was made relatively difficult. In both conditions, a facilitative effect was apparent at the 150-msec SOA and an inhibitory effect was apparent at the 750-msec SOA for both accuracy and response time measures of performance. That these results were apparent for a judgment unrelated to the manipulated cue-target relation suggests strongly that both location-based and frequency-based auditory inhibition of return result primarily because of changes in perceptual sensitivity.     

Perception without awareness: further evidence from a Stroop priming task

In the present research, we examined the influence of prime-target stimulus onset asynchrony (SOA) on Stroop-priming effects from masked words. Participants indicated the color of a central target, which was preceded by a 33-msec prime word followed either immediately or after a variable delay by a pattern mask. The prime word was incongruent or congruent with the target color on 75% and 25% of the trials, respectively. The words followed by an immediate mask produced reliable Stroop interference at SOAs of 300 and 400 msec but not at SOAs of 500 and 700 msec. The words followed by a delayed mask produced a reversed (i.e., facilitatory) Stroop effect, which reached significance at an SOA of 400 msec or longer, but never at the shorter 300-msec SOA. Such an differential time course of both types of Stroop priming effects provides further evidence for the existence of qualitative differences between conscious and nonconscious perceptual processes.     

Automatic and attentional processes in the comprehension of unfamiliar metaphors

The present study employed priming techniques to investigate whether unfamiliar metaphors are understood automatically, or whether controlled processes are required for comprehension. Priming sentences were presented to 76 participants in a naming task and vocal RT (reaction time) to target words was recorded. Target words were associates of the 120 metaphors used in the stimulus set. SOA (stimulus onset asynchrony) was manipulated in order to permit the measurement of both automatic and attentional priming (375ms, 750ms, and 1,500ms). Four priming conditions enabled a comparison between metaphoric, literal, and neutral contexts, and an unrelated (baseline) condition. The data revealed a strong priming effect for metaphors at an SOA of 1,500ms, but no effects at either of the shorter SOAs. These results indicate that, in the absence of supporting context, unfamiliar metaphors are not processed automatically. Comprehension of such linguistic phenomena apparently requires attentional processing. The findings have implications for direct processing theories of metaphor comprehension.     

Automatic and attentional processes in the comprehension of unfamiliar metaphors

The present study employed priming techniques to investigate whether unfamiliar metaphors are understood automatically, or whether controlled processes are required for comprehension. Priming sentences were presented to 76 participants in a naming task and vocal RT (reaction time) to target words was recorded. Target words were associates of the 120 metaphors used in the stimulus set. SOA (stimulus onset asynchrony) was manipulated in order to permit the measurement of both automatic and attentional priming (375ms, 750ms, and 1,500ms). Four priming conditions enabled a comparison between metaphoric, literal, and neutral contexts, and an unrelated (baseline) condition. The data revealed a strong priming effect for metaphors at an SOA of 1,500ms, but no effects at either of the shorter SOAs. These results indicate that, in the absence of supporting context, unfamiliar metaphors are not processed automatically. Comprehension of such linguistic phenomena apparently requires attentional processing. The findings have implications for direct processing theories of metaphor comprehension.