Selective attention and priming: Inhibitory and facilitatory effects of ignored primes

The priming effects of ignored information have been studied in Stroop displays (Neill, 1977) and with spatially superimposed drawings (Tipper, in this issue); naming of probes related to ignored primes is delayed in these experiments (“negative priming”). This negative priming effect is confirmed in a list reading task in Experiment 1, which used partially superimposed letters, and Experiment 2, which used spatially separated letters. Furthermore, Lowe (1979) using Stroop colour words observed that changing the nature of the probe such that it did not require selection from a competing word reversed the priming effects of the ignored word from inhibition to facilitation. Experiment 3 confirmed this observation when subjects selected a red letter from a green letter. Two models are suggested to account for this result. In the first, negative priming is a product of the ignored prime and subsequent probe being encoded both as a stimulus to be ignored and one to be named (Allport, Tipper and Chmiel, in press; Lowe, in press). This dual encoding is ambiguous, requiring further processing before response can be output. The other model suggests that negative priming reflects inhibition of response to ignored information, slowing naming latencies to probe stimuli that require the same response. Experiment 4 attempts to differentiate between the models, and the latter inhibition view is preferred.     

Bias effects in facilitatory phonological priming

In four experiments, we examined the facilitation that occurs when spoken-word targets rhyme with preceding spoken primes. In Experiment 1, listeners' lexical decisions were faster to words following rhyming words (e.g., ramp-LAMP) than to words following unrelated primes (e.g., pink-LAMP). No facilitation was observed for nonword targets. Targets that almost rhymed with their primes (foils; e.g., bulk-SULSH) were included in Experiment 2; facilitation for rhyming targets was severely attenuated. Experiments 3 and 4 were single-word shadowing variants of the earlier experiments. There was facilitation for both rhyming words and nonwords; the presence of foils had no significant influence on the priming effect. A major component of the facilitation in lexical decision appears to be strategic: listeners are biased to say "yes" to targets that rhyme with their primes, unless foils discourage this strategy. The nonstrategic component of phonological facilitation may reflect speech perception processes that operate prior to lexical access.     

Differential effects of prime-probe duration on positive and negative location priming: Evidence for opponent facilitatory and inhibitory influences in priming tasks

A series of four spatial localization experiments is reported that examined the effects of display duration and presentation mode on positive and negative priming using an attended-repetition and an ignored-repetition paradigm, respectively. Experiment 1 showed larger positive priming with response-dependent than with 150 ms display durations while negative priming remained unaffected. Experiments 2-4 were performed to further elucidate the effects of prime-probe durations. Data suggest largely independent effects of prime and probe duration on priming effects. Manipulation of prime duration affected facilitation due to repetition of the prime distractor location as well as inhibitory effects associated with ignored repetition. Furthermore, anticipated probe duration modulated the effectiveness of inhibition of return. Findings are discussed within a framework proposing two major components of priming effects—a stimulus-driven or automatic component, and a strategic component related to the participant's expectations towards the probe.     

Inhibitory and facilitatory effects of cue onset and offset

The response speed to a visual target is modulated by the position of previous events (cues) even if their position is not predictive of the target position. The modulation has been considered biphasic, with an early facilitatory and a later inhibitory component. We conducted three experiments that investigated the importance of the onset and offset features of the cue for the facilitatory and inhibitory effects and estimated their separate and joint effects. The two possible target locations, one in the right and one in the left visual field, were indicated by two empty boxes, and the cue consisted of the onset and/or offset of an arrowhead located just under one of the two boxes. Different time intervals were used between cue and target. Subjects were instructed to ignore the cue and to respond to the target (a cross inside one of the two boxes). The data showed only consistent effects of inhibition (inhibition of return) with the long intervals, but the pattern was different depending on the cue type. The amount of inhibition was much greater when the onset of the cue was followed by its offset. Apparently, inhibition of return depended on the dynamic changes of the cue. Received: 23 October 1996 / Accepted: 3 June 1997     

Timing of facilitatory and inhibitory effects of visual attention

Three experiments were conducted to investigate influences on the precue-to-target delay at which response facilitation is first replaced by inhibition of return (IOR). In Experiment 1, different ranges of delays were used; the interpolated delay at which faster RTs for matching precue and target locations changed to slower RTs was inversely related to the length of the range of precue-to-target delays within a block of trials. These findings were replicated in Experiment 2, which additionally showed that task difficulty provided an insufficient explanation for the delay in the changeover time. These data allowed the conclusion that a shorter range of precue-to-target delays results in later onset of IOR than does a longer range of delays. The data from Experiment 3 suggested that a single character on the target screen confounds the interpretation of possible facilitation and/or inhibition due to the allocation of attention. These results were related to other reported findings and to theories of attention allocation.     

The control of visual attention and its influence on prioritized processing in a location negative priming paradigm

In a location-based negative priming paradigm, the possibility of a disengagement option of the underlying inhibitory mechanism was tested. Whereas in previous studies disengagement was observed when providing utility information about the probe trial structure, in the present study the allocation of visual attention to the stimuli was manipulated. In the first step an automatic deployment of visual attention was implemented by presenting all stimuli as abrupt onsets (Experiment 1), which demonstrated commonly observed negative priming effects. In further conditions of non-automatic allocation of visual attention in which target and distractor were presented as no-onset stimuli, negative priming effects were eliminated (Experiments 2 and 3). The preferred interpretation is that in conditions of automatic control of attention, target and distractor compete for control of action. A non-automatic control of visual attention, on the other hand, leads to a top-down modulated selection, which results in prioritized target encoding and a loss of distractor impact on the selection process. Alternative accounts and the role of no-onset distractor processing were investigated in Experiment 4.     

Attentional priming and visual search in pigeons

Advance information about a target's identity improved visual search efficiency in pigeons. Experiments 1 and 2 compared information supplied by visual cues with information supplied by trial sequences. Reaction times (RTs) were lower when visual cues signaled a single target rather than two. RTs were (Experiment 1) or accuracy improved (Experiment 2) when a sequence of trials presented a single target rather than a mixture of 2. Experiments 3, 4, and 5 considered the selectivity of visual priming by introducing probe trials that reversed the usual cue-target relationship. RT was higher following such miscues than following the usual 1- or 2- target cuing relationships (Experiment 3); the miscuing effect persisted over variations in the target's concealment (Experiments 4 and 5), but did not occur when the target was presented alone (Experiment 4). The findings indicate that priming modifies an attentional mechanism and suggest that this effect accounts for search images.     

Object- and feature-based priming in visual search

Two contrasting accounts for priming in visual search have been proposed. The main difference between the two is the level of perceptual processing at which the priming effects are assumed to occur, whether priming is assumed to operate through the selective facilitation of features or at the level of selection of objects for response. The aim of the experiments here was to contrast these accounts. In the first two experiments, observers performed a search for the odd diamond in the midst of two distractor diamonds. Each diamond had two colors, but the configurations of the colors within the diamonds were different for the two experiments in ways previously shown to lend themselves differently well to object formation. The results show that priming can be both feature- and object-based, depending on the topological properties of the stimuli. This was confirmed in a third experiment, in which a quite dissimilar stimulus set was used to address the same question, once again yielding similar results. We thus show that priming operates at various levels of perceptual processing, a result consistent with new findings from neuroimaging and neuropsychology.     

Semantic priming and retrieval from lexical memory: Evidence for facilitatory and inhibitory processes

Immediately prior to each visually presented target letter string to which the subject made a speeded word-nonword classification response, a visually presented prime to which no overt response was required was shown for 360, 600, or 2,000 msec. For word (W) target trials, the priming event was either a semantically neutral warning signal (Condition NX), a word semantically related to the target word (Condition R), or a word semantically unrelated to the target word (Condition U); for nonword (N) target trials, the priming event was either the neutral warning signal (Condition NX) or a word prime (Condition WP). For the W target trials, reaction times (RTs) were slower in Condition U than in Condition NX and equally so for all three prime durations; RTs were faster in Condition R than in Condition NX and to a greater degree for the 600- and 2,000-msec prime durations than for the 360-msec prime duration. For the N targets, RTs were faster in Condition WP than in Condition NX and equally so for all prime durations. These results were interpreted within the framework of a two-factor theory of attention proposed by Posner and Snyder (1975a).     

Dissociations between identity and location negative priming

Negative priming refers to the phenomenon of a slowed response time to a previously ignored distractor. Identity negative priming can be observed when the identity of a previous distractor is repeated as the target identity, and location negative priming can be observed when the spatial location of a previous distractor is repeated as the target location. This article reviewed and integrated previous findings and provided empirical evidence to show the dissociations between location and identity negative priming: (a) the removal of probe distractor impeded identity negative priming but not location negative priming; (b) identity negative priming was modulated by the distance between the target and distractor, while location negative priming was not; and (c) perceptual grouping of the target and distractor affected identity negative priming but not location negative priming.     

Disengaging the negative priming mechanism in location tasks

In a location-based negative priming task, targets that appear at locations that were previously occupied by distractors are typically responded to more slowly than are targets that appear at formerly unoccupied positions. In the present study, we attempted to disengage the location-based negative priming mechanism by presenting visual cues indicating the most likely location of the upcoming target. The first experiment showed that 75% cue-target validity was not sufficient to affect the negative priming mechanism. However, the second experiment demonstrated that a much reduced, but not eliminated, negative priming effect occurred with 100%cue-target validity. These findings are similar to those found with inhibition of return, suggesting that location-based inhibition of return effects and location-based negative priming effects may share a common inhibition mechanism.     

Repetition priming in visual search: Episodic retrieval,not feature priming

Previous research has shown that when the targets of successive visual searches have features in common, response times are shorter. However, the nature of the representation underlying this priming and how priming is affected by the task remain uncertain. In four experiments, subjects searched for an odd-sized target and reported its orientation. The color of the items was irrelevant to the task. When target size was repeated from the previous trial, repetition of target color speeded the response. However, when target size was different from that in the previous trial, repetition of target color slowed responses, rather than speeding them. Our results suggest that these priming phenomena reflect the same automatic mechanism as the priming of pop-out reported by Maljkovic and Nakayama (1994). However, the crossover interaction between repetition of one feature and another rules out Maljkovic and Nakayama's (1994) theory of independent potentiation of distinct feature representations. Instead, we suggest that the priming pattern results from contact with an episodic memory representation of the previous trial.     

Automatic phonological priming in visual word recognition

Theories of visual word recognition have proposed that a word’s phonological properties can be involved in reading visually presented words. Further, it is commonly supposed that this phonological information can be arrived at in at least two ways: (1) by looking it up after identifying the word visually (a lexical route) or (2) by rule-governed translating of the word’s orthographic code (a nonlexical route), Four experiments were conducted to examine whether phonological information is automatically accessed in visual word recognition, and, if so, how this occurs. A priming technique was used with a display sequence of mask, prime, target, mask. Subjects were asked to make written responses to any words that they thought were present, and prime identification was minimal. A facilitatory effect of phonological priming on target identification occurred when primes were homophones of targets. However, no similar facilitation occurred when the prime was a nonword homophone of the target. Further, the homophone priming effect was found irrespective of whether targets followed the spelling-to-sound rules of English. The results suggest that automatic access to phonology can occur in visual word recognition and that it operates by means of a lexical route.     

Emotional priming of pop-out in visual search

When searching for a discrepant target along a simple dimension such as color or shape, repetition of the target feature substantially speeds search, an effect known as feature priming of pop-out (V. Maljkovic and K. Nakayama, 1994). The authors present the first report of emotional priming of pop-out. Participants had to detect the face displaying a discrepant expression of emotion in an array of four face photographs. On each trial, the target when present was either a neutral face among emotional faces (angry in Experiment 1 or happy in Experiment 2), or an emotional face among neutral faces. Target detection was faster when the target displayed the same emotion on successive trials. This effect occurred for angry and for happy faces, not for neutral faces. It was completely abolished when faces were inverted instead of upright, suggesting that emotional categories rather than physical feature properties drive emotional priming of pop-out. The implications of the present findings for theoretical accounts of intertrial priming and for the face-in-the-crowd phenomenon are discussed.     

Inhibitory stroke neighbour priming in character recognition and reading in Chinese

In alphabetic languages, prior exposure to a target word's orthographic neighbour influences word recognition in masked priming experiments and the process of word identification that occurs during normal reading. We investigated whether similar neighbour priming effects are observed in Chinese in 4 masked priming experiments (employing a forward mask and 33-ms, 50-ms, and 67-ms prime durations) and in an experiment that measured eye movements while reading. In these experiments, the stroke neighbour of a Chinese character was defined as any character that differed by the addition, deletion, or substitution of one or two strokes. Prime characters were either stroke neighbours or stroke non-neighbours of the target character, and each prime character had either a higher or a lower frequency of occurrence in the language than its corresponding target character. Frequency effects were observed in all experiments, demonstrating that the manipulation of character frequency was successful. In addition, a robust inhibitory priming effect was observed in response times for target characters in the masked priming experiments and in eye fixation durations for target characters in the reading experiment. This stroke neighbour priming was not modulated by the relative frequency of the prime and target characters. The present findings therefore provide a novel demonstration that inhibitory neighbour priming shown previously for alphabetic languages is also observed for nonalphabetic languages, and that neighbour priming (based on stroke overlap) occurs at the level of the character in Chinese.     

Inhibitory neighbor priming effects in eye movements during reading

We report an eye movement experiment investigating whether prior processing of a word’s orthographic neighbor in a sentence influences subsequent word processing during reading. There was greater difficulty in early word processing when a target word’s neighbor rather than a control word appeared earlier in a sentence; this effect was uninfluenced by the relative lexical frequency of the word and its neighbor. We discuss this inhibitory neighbor priming effect in terms of competitive network models of word recognition and the process of lexical identification in the E-Z Reader model of oculomotor control (e.g., Reichle, Pollatsek, Fisher, & Rayner, 1998).     

The role of visual attention in action priming

It has been demonstrated that the task-irrelevant left–right orientation of an object is capable of facilitating left–right-hand responses when the object is orientated towards the responding hand. We investigated the role of attention in this orientation effect. Experiment 1 showed that object orientation facilitates responses of the hand that is compatible with the object's orientation, despite the entire object being irrelevant. However, when a task-relevant fixation point was displayed over the prime object in Experiment 2, the effect was not observed. Together Experiments 1 and 2 suggest that the orientation information of viewed objects primes the action selection processes even when the object is irrelevant, but only when attention is not allocated to a competing stimulus during the prime presentation. Experiment 3 suggested that the elimination of the effect in Experiment 2 could not be attributed to the elimination of an attentional shift to the graspable part of the prime. Finally, Experiment 4 showed that object orientation can evoke an abstract response code, influencing the selection of finger responses.     

Age-related reduction in 3-D visual motion priming

In 3 experiments, younger and older adults judged the perceived motion of three-dimensional (3-D) figures that rotated in depth either unambiguously or ambiguously. Both groups were found to be equivalent in judging the direction of single rotations of the simulated 3-D objects (Experiment 1). In Experiments 2 and 3, a single unambiguous rotation (prime) was followed 0-3200 ms later by an ambiguous rotation (target). Motion priming was indicated by the disambiguation of the second rotation by the first rotation. 3-D motion priming was initially found to be similar in young and old, but it rapidly reduced in the older participants compared to the younger ones. Using a nonluminance depth cue--occlusion--to induce 3-D motion, diminished contrast sensitivity in the elderly was ruled out as a cause of the reduced priming. The results show that 3-D motion priming exhibits robust age-related decline. An age-related decrease in temporal persistence may account for the reduction in 3-D motion priming in older adults.     

The role of visual attention in action priming

It has been demonstrated that the task-irrelevant left-right orientation of an object is capable of facilitating left-right-hand responses when the object is orientated towards the responding hand. We investigated the role of attention in this orientation effect. Experiment 1 showed that object orientation facilitates responses of the hand that is compatible with the object's orientation, despite the entire object being irrelevant. However, when a task-relevant fixation point was displayed over the prime object in Experiment 2, the effect was not observed. Together Experiments 1 and 2 suggest that the orientation information of viewed objects primes the action selection processes even when the object is irrelevant, but only when attention is not allocated to a competing stimulus during the prime presentation. Experiment 3 suggested that the elimination of the effect in Experiment 2 could not be attributed to the elimination of an attentional shift to the graspable part of the prime. Finally, Experiment 4 showed that object orientation can evoke an abstract response code, influencing the selection of finger responses.     

Probability cuing of target location facilitates visual search implicitly in normal participants and patients with hemispatial neglect

We explored how variability in the probability of target locations affects visual search in normal individuals and in patients with hemispatial neglect, a deficit in attending to the contralesional side of space. Young and elderly normal participants responded faster when targets appeared in the more probable region than when targets appeared in the less probable region. Similarly, patients were sensitive to the distribution of targets, even in the neglected field. Although the attentional gradient that characterizes neglect was not eliminated, the response facilitation due to the probability distribution was proportionate to that of control participants and equal in magnitude across the neglected field. All participants exploited the uneven distribution of targets to enhance task performance without explicit instructions to do so or awareness of biases in their behavior. These results suggest that attentional orientation and sensitivity to external probabilities are possibly dissociable. An early sensory and a late motor mechanism are postulated as possibly being involved in the observed probability–matching behavior of participants.