PS: Introduction to Psycholinguistics Winter Term 2005/06 Instructor: Daniel Wiechmann Office hours: Mon 2-3 pm Phone: Web:

Session 3: Visual processing Sensory input Perceptual organization Object Recognition Buttom-up processing - Visual processing originates from sensory input Experience

Session 3: Visual processing Sensory input Perceptual organization Object Recognition Prior Experience Top-down processing

Session 3: (visual) word recognition Word level Letter level Feature level CAT Assumption: word recognition sequential buttom-up-process

Session 3: (visual) word recognition

Word level Letter level Feature level Stimulus: COAT top-down effects (word superiority effect) buttom-up effects

Session 3: (visual) word recognition

Summary - word recognition is a combination of buttom-up sensory information and top-down knowledge - word recognition is bi-directional (not sequential) and graded (not discrete) - interactive activation model violates the sequential and discreteness assumptions of a strict information processing model

Session 3: (visual) word recognition/ methods  Methods to explore visual recognition Brain imaging Examining eye movements Word identification tasks Categorisation times Tachistoscopic identification

Session 3: (visual) word recognition/ methods  word identification techniques Naming task Subjects name visually presented a words Naming latency is measured (RT ~ 500ms from onset of stimulus) Lexical decision task Subjects decide whether string/sequence is a word or not RT and error rate is measured

Session 3: (visual) word recognition/ methods  Eye movement in reading e.g. Limbus tracking Infra red beam is bounced off the eyeball and tracks the the boundary between the iris and the white of the eye (limbus)

Session 3: (visual) word recognition/observations  Reading involves rapid ‘jumps’ called saccades ( ms in duration); length is about eight letters 10% of all saccades move backwards  Average fixation times range between ms Information retrieval takes place in that interval Average span: 15 to the right, 3-4 left (for left to right processing)

Session 3: (visual) word recognition/observations

Session 3: Towards a model of reading  a simple model model Readers fixate on a word until they have processed it sufficiently Then eyes move to the next word

Session 3: Towards a model of reading  But... Only 80% content words are fixated Only 20% of function words are fixated Rare words are fixated longer than common words Words that are more predictable in sentence context are fixated for less time Words that are not fixated tend to be common, short, or predictable Fixation time of a word is longer when it is preceded by a rare word (spillover effect)

Session 3: Towards a model of reading  Problems for the simple model: It is hard to see how readers could skip words It takes about ms to execute an eye- movement program -> readers would waste time waiting for their eyes to move

Session 3: Towards a model of reading  Advantages eye-movement recording: It provides a detailed on-line record of attention- relation processes Unobstrusive  Disadvantage Hard to to be sure exactly what processing occurs during each fixation

Session 3: Towards a model of reading  E-Z reader model (Reichle 1998) Readers check frequency (F) of fixated word Completion of F-check is the signal to initiate eye-movement program

Session 3: Towards a model of reading  E-Z reader model (Reichle 1998) Readers also engage in lexical access (identify orthographic and/or phonological pattern so that semantic information can be retrieved) Completion of lexical access is signal for shift of attention to the next word

Session 3: Towards a model of reading  E-Z reader model (Reichle 1998) cont.: F-check and lexical access are faster for common words (due to organization of mental lexicon) F-check and lexical access are completed faster for predictable words

Session 3: Towards a model of reading: E-Z reader model Effects of word frequency on eye-movements Time between successive eye- movements in ms Frequency

Session 3: Towards a model of reading: E-Z reader model  Parafoveal processing Readers spend time between completion of lexical access to a word and next saccade in parafoveal precessing of the next word (this way the model can explain spillover effect)

Session 3: (visual) word recognition/observations  fovea ~ most sensitive part of the visual field (2 degrees either side of fixation point  parafovea (extending 5 degrees)  periphery

Session 3: Automatic processing  Word recognition is fairly automatic Reading is mandatory (cf. Stroop effect) How many mechanisms are involved? Automatic processes: (fast, parallel, not prone to interference from other tasks, cannot be prevented, facilatatory) Attentional (controlled) processes: slow, serial, error prone, uses up working memory (WM), often availble to consciousness, can involve inhibition)

Session 3: Priming  Priming Involves the presentation of an item A (prime) before reaction to item B (target) is measured stimulus-onset asynchrony (SOA) facilitation vs. Inhibition Form-based priming Semantic priming

Session 3: Priming  Context effects Semantic (associative) priming Lexical decision task  Decision time for target is shorter when prime is semantically related (e.g. DOCTOR - NURSE)

Session 3: Priming  Priming from sentential context “It is important to brush your teeth every single ___!”